There comes a time in winter when your heat pump will ice buildup. The machine will enter the defrosting cycle setting to combat and melt the snow. But, if the mode does not work properly, there is some serious issue with your unit.

Major issues are bad thermostats, poor drainage, a faulty reversing valve, low refrigerant, and electrical issues. Possible fixes include checking the thermostat, clearing the drainage, replacing the reversing valve and refrigerant tube, and fixing the wires. 

You may troubleshoot some issues, but most require expert guidance and help. This article will explore all the possible causes of why the heat pump does not defrost and how to troubleshoot and prevent the problem. 

What is a defrost cycle, and how does it work?

The ice development process on the outside coils is slow when your heat pump functions.

When the thermostat senses a drastic drop in the temperature, it will shift from a heating to a cooling process with the help of the reversing valve. 

As a result, the defrost mode will start working on unfreezing the ice buildup in your heat pump. 

The evaporator becomes the condenser during the defrost mode.

The heat pump must regularly defrost during the frost, and the cycle should be long enough to melt all the snow and short enough to save energy. 

The defrost relay allows the cycle to keep going for 30 minutes. 

When the heat pump is in cooling mode, the outdoor fan will stop working, and the inside device will stop moving the air inside. 

As a result, it leads to high temperatures and defrosting operations. 

The process may last for 5 to 10 minutes, or even more, based on the thickness of the snow layer. 

The reversing valve and the evaporator will work together, and the high-pressure refrigerant will warm up and defrost all the snow from your unit. 

The thermostat will wait for your unit to return to its normal temperature and stop the defrosting procedure. 

Once the defrost stops, the unit will begin normal heating. 

The freezing will start again if the temperature becomes too low for the unit to handle. 

The old heat pumps also have the defrost mode but do not have thermostats or sensors for signaling. 

Instead, they have timers that allow the defrost to work for a specific time. 

But, the problem with timers is the defrost will work at a specific, with or without ice buildup. 

As a result, this procedure reduces your unit’s efficiency and increases energy bills. 

When does the heat pump start defrosting?

There are situations and times when the heat pump should start defrosting and how. There are those circumstances:

Temperature differences indoor vs. outdoor

When the thermostat or sensor on the outdoor coil’s bottom senses the temperature is very low compared to the outside temperature, the defrost cycle will start immediately. 

It happens if the temperature is as high as 60°F or as low as 30°F. 

Once the outdoor coil’s thermostat reaches close to 60°F, the coil will defrost, and the cycle will stop. 

Air pressure

The space between the coils becomes impenetrable when the coil starts having a layer of ice. 

As a result, the air struggles to pass through the coils and increases the pressure. 

When the air pressure increases, the defrost cycle will start working immediately with the help of a differential switch. 

The switch turns on when the pressure is too high and turns off when the pressure comes back to normal. 

Timer and thermostat

The unit will have a timer and thermostat or sensor that helps turn on the defrost cycle. 

The method is better than the above two. 

The devices measure the temperature every 90 minutes and turn on the defrost mode based on the sensor. 

Why is my heat pump not defrosting?

When the evaporator defrosts, the hot refrigerator is directed to the coil, and the outside fan stops working to speed up the process. 

The compressor moves the refrigerant and increases the pressure. 

You can confirm it by hearing a humming noise when the compressor works, a whooshing noise once the defrost cycle is over, and white steam blowing out of the unit. 

If any methods fail to work properly, the defrost cycle won’t work. 

As a result, the heat pump won’t defrost, and the heating capacity gets compromised. 

Here are some common reasons behind a heat pump not defrosting:

1. The unit is covered with ice and snow.

Ice buildup is common in colder climates. 

If your heat pump is completely covered with snow, it won’t be able to defrost properly. 

You need to melt some ice and let your unit start the defrost cycle. 

Avoid using sharp objects. 

Try running water with a garden hose or pouring hot, warm over the snowy areas. 

2. Drainage issues

Leaves, sticks, snow, and other debris can clog the drainage system and affect the defrost cycle of the unit. 

Due to the blocked drainage system, the water will be accumulated inside the device instead of draining out. 

The water will remain inside your unit, freeze over the other components, and affect their capacity to perform appropriately.

Sometimes, the ice blocks will be too thick for the defrost cycle to break. As a result, the defrost cycle will not work properly. 

Clear everything from your unit and clean the drainage systems to troubleshoot the problem. 

Trim the overhead branches and twigs to stop them from dripping water over your unit. 

The gutters should be empty and in good condition. 

3. Low refrigerant 

The refrigerant or coolant helps in cooling or heating the air of your house. 

The refrigerant gets pumps through the evaporator coils to heat them and defrost the heat pump. 

The heat pump’s defrost cycle depends on this coolant. 

The refrigerant extracts heat from the outdoor air to move it to the evaporator coils and other condensers that require warmth for melting ice. 

If the refrigerant is low, there won’t be enough heat to encourage the defrosting cycle to start. 

Besides this, the pressure and temperature will reduce inside the pump, affecting the defrost cycle negatively. 

The leakage can be caused due to cracks, erosion, and rust. 

You should hire an HVAC expert to deal with it.

4. Bad reversing valve

The reversing valve changes the direction of the refrigerant flow from cooling to heating. 

The valve can malfunction by getting stuck in the heating or cooling position. 

When the reversing valve fails to do its job due to malfunctioning, the heat pump won’t enter the defrost mode. 

It will start building more ice and worsen your unit’s condition. 

You should call an HVAC to deal with the valve. 

5. Bad thermostat, sensor, or timer

The defrost cycle startup depends on the thermostat or the heat pump’s timer that signals the unit to start the cycle. 

The thermostat or the timer also decides the running time of the defrost mode. 

If the thermostat or the timer malfunctions, the unit won’t enter the defrost mode to start the cycle. 

Even if the unit enters the mode, it will fail to defrost the ice. 

The thermostat or timer malfunction occurs due to poor sensors or communications. 

You should hire an HVAC expert to fix the thermostat and timers. 

6. Damaged or blocked outdoor coil

The outdoor unit has a condenser coil to enable the heat exchanger. 

In the cooling mode, the condenser coil transfers the warm air outside your house. 

In the heating mode, it transfers the warm air to the coolant, which changes it to cold air and circulates it inside your house. 

The coils have enough space for the maximum heat exchangers. 

If the coils get damaged due to rust or get blocked due to dirt and debris, it can lead to a refrigerant leak. 

As a result, the defrost mode will not work properly. 

Check the coil for signs of damage. 

Since the coils are difficult to access, call your HVAC team to check them and clean or replace them. 

7. Improper installation 

You can expect an improper unit installation when a heat pump does not defrost properly. 

You should install the heat pumps by taking help from the heating and cooling company excelling in heat pumps. 

Some common installation mistakes include:

• Refrigerant is poorly charged
• Kink in the refrigerant line due to carelessness
• A place with insufficient airflow
• Installed over a flat or low surface

You should call a professional to look into your unit if you suspect improper installation.  

8. Electrical or wire issues

Wires are the electrical issues through which current passes to the heat pumps and other components. 

Suppose the wires are damaged, loose, or frayed. In that case, the connection between the components will damage, and the defrost cycle will never start. 

You should hire an electrician to fix the wires. 

9. Insufficient fan power

The heat pump fan helps start or end the defrost cycle. 

If the fan does not start or its power is insufficient, the heat pump will start several issues. 

Defrost not working is one of them. 

The defrost cycle gets stuck when the fan works backward and never starts again. 

Call an HVAC expert to fix the fan. 

What to do when the defrost does not work in the heat pump?

You can resolve the problems that lead to the defrost issue by yourself or by seeking help from the HVAC expert team. 

To prevent the problem from further occurring, follow the following steps:

Remove leaves and debris from the outdoor coil.

Make sure to clean the surrounding of the outdoor coil always, especially during the snowy winter and after windy weather. 

Keep the leaves, twigs, snow, and branches away from the unit. 

Clean the internal areas.

Check the internal components like the timer, relay, reversing valve, motor, and other things to ensure they are in good shape. 

Call an HVAC if you suspect anything.

Install an EDIDS

EDIDS stands for Energy Docs Intelligent Defrost System. 

It is a sensor, timer, and thermostat system that generates faster defrost cycles and produces adequate delivery to help your unit work efficiently. 

It also adds a pressure sensor to the thermostat and the timer to measure the temperature whenever the timer tells the thermostat to do so. 

Whenever the pressure and temperature drop low, the defrost will start immediately and keep running until both come to a proper level. 

With EDIDS, the defrost cycle will start when it is required. 

The original system is built only on time and temperature. 

The EDIDS will make your heat pump better and more intuitive. 

Give the unit some time.

Sometimes, it is not a problem, and not resolving, or prevention is required. 

Your heat pump requires some time to deliver the results.

Generally, the unit takes several minutes after you notice the ice layer. 

The older heat pumps will need more time to start the defrost cycle. 

Run the fan

Running the fan can help the heat pump to melt the ice if the defrost refuses to start. 

Running the fan with the heating in off mode will thaw the coil within one hour. 

Set your fan to exhaust mode if the outdoor temperature is too low. 

Thawing will not solve the frost issue completely, but it should help your heat pump to run back again. 

Check the thermostat 

The defrost setting should be correct in the thermostat. 

The defrost cycle mostly starts when the outdoor temperature goes below 31°F. 

If the setting in the thermostat is lower, adjust it properly. 

Defrost manually

The energy-saving settings may interfere with the defrost cycle and prevent the automatic defrost cycle from starting. 

Most modern heat pumps have a manual defrost system where you can run the defrost cycle by pressing a button. 

If your unit has such a system, press the defrost button to run the cycle manually. 

Maintain regular maintenance

Maintain routine maintenance and servicing by the HVAC team every year. 

The team will inspect the condition of your heat pump and its components and inform you if any repair or replacement is required. 

The members can fix if any repair is needed and help in the smooth functioning of your unit.

Final thoughts

Since a heat pump is a machine, it won’t come without a flaw. 

If your heat pump does not defrost, you should inspect your unit. 

Cross-check with every reason explained in this guide to find out why the heat pump refuses to defrost. 

Do not use any sharp or hard objects to remove the ice buildup. 

The fan coils are delicate, and using hard objects will damage them. 

Check for the thermostat, sensors, drainage, refrigerant level, outdoor units, reversing valves, and electrical parts. 

These are some common grounds where malfunctioning will negatively affect the defrost cycle.

Eventually, call an HVAC if you face complications or hesitation in inspecting the unit. 

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A heat pump can provide you with both cooling and heating systems efficiently. But every gadget comes with a flaw. Heat pumps will short cycle, which reduces the unit’s ability to warm or cool your house and increases energy bills. 

The primary reasons behind a heat pump’s short cycling are oversized units, thermostat issues, clogged air filters, and refrigerant leakage. Get the right unit size, correct the thermostat settings, change the filters, and call an HVAC to fix the refrigerant tubes. 

Besides these major causes, there are more reasons responsible for short cycling. Today, we will discuss how to diagnose short cycling, explore the reasons behind it, and the ways of troubleshooting them.

What is short cycling?

It is called short cycling when your heat pump turns on and shuts down after a few seconds or minutes before completing its heat cycle. 

Your system will constantly run in its startup phase and not at optimal efficiency. 

Is short cycling normal?

Short cycling in the heat pump is not at all normal. 

Short cycling will put too much strain on the unit’s components and reduce the efficiency and lifespan of your unit faster. 

Every time the unit jump starts, the energy bill increases too much.

So, whenever your unit is short cycling, you must find its real cause and solve it soon. 

Though short cycling may seem harmless, it can cause significant damage to both the heating and cooling systems. 

The short bursts of power will be tough for the system to handle and result in faster wear out. 

How many times should a heat pump start the heating cycle?

There is no exact answer to this question because a heat pump starts depending on various factors like the outside temperature, the room temperature, and the heat pump type. 

Generally, most heat pumps should turn the cycle on and off every 30 to 60 minutes, which means 1 to 2 cycles per hour.

Sometimes, the unit will run 2 to 3 cycles per hour, depending on the indoor and outdoor temperature. 

A heat pump should constantly run for only 10 to 20 minutes, neither more nor less. 

If the unit shuts off before the heating cycle is complete, it is short cycling. 

Since it is not normal, you must figure out why.

Why does the heat pump have short cycles?

Heat pumps are a complex mechanism for inexperienced people. 

Some house owners do not even know how to figure out the reason behind the quick on and off. 

You may solve some problems yourself, but others require HVAC attention. 

To know whether a problem requires an HVAC, you must inspect what is wrong with your unit. 

So, here are some common reasons behind the short cycling of the heat pump:

1. Thermostat issues

A thermostat plays a great role in the heat pump’s functionality. 

It signals your unit to turn on and off during the start and end of the heating cycles. 

It also determines other things like the emergency heat, constant running of the fan, the desired temperature, humidity, etc. 

A thermostat issue includes a lot of things:

Poor device placement 

Poor placement of the thermostat will interfere with the accurate record of the room temperature, which can lead to the short cycling of the heat pump. 

Suppose your thermostat is located in a place with direct sunlight. 

The device will heat up quickly due to the sun’s heat and signal the unit to turn off before it completes the heating cycle. 

The short cycling will occur every time you turn it on. 

As a result, the unit’s efficiency will decrease, and your energy bills will increase. 

Wire issues

The next thermostat issue is with the wires. 

Frayed or damaged wires will also interrupt the signal and make your heat pump short cycle. 

You must change the thermostat’s position and keep it in a central position in your house. 

Consult an HVAC for the best position. 

If the wires are the problem, you should hire a professional to fix them. 

Temperature setting problem 

When you set a temperature to an extreme level, the heat pump will constantly turn on and off. 

The heat pump will try to give you the desired temperature while maintaining the room temperature. 

As a result, the heat pump will frequently short cycle and overheat your unit. 

When you set the temperature too low, the heat pump will have to work overtime to give you the desired temperature and maintain the room temperature. 

Overworking will stress the unit too much, get overheated, and result in frequent short cycles.

The best option is to set a consistent and average temperature to keep your thermostat and heat pump in good shape.

The average temperature to set in the heat pump’s thermostat throughout the year would be around 65 to 70°F, 68°F being the best choice.

If you wish to change the level due to the outdoor temperature, increase or decrease it by only 5 degrees. 

2. Wrong size of the unit

Based on the house’s square footage, the size of the heat pumps will differ. 

An oversized heat pump heats your room faster and shuts down after a few minutes before the heating cycle ends. 

Besides, a larger unit will need more power to heat your room and increase your energy bills. 

With the right heat pump size, the heat cycles will end when they should, and your house will have comfortable warm air. 

If you suspect your heat pump to be oversized, hire a local HVAC expert to help you with the size and recommend the right one. 

You must know the square footage of your house to know the right heat pump size, as that is how it is determined. 

A small guide to heat pump size:

• 500 square feet – 1 ton or 12,000 BTU heat pump
• 1,000 square feet – 2 tons or 24,000 BTU heat pump
• 1,500 square feet – 3 tons or 36,000 BTU heat pump
• 2,000 square feet – 4 tons or 48,000 BTU heat pump

3. Clogged air filters

The air filter filters the air absorbed by the unit and traps the air particles. 

Over time, the filter will become clogged with dirt and debris. 

If you do not change the filter from time to time, the heat pump will struggle to release the air and distribute it evenly around the house. 

As a result, most of the air will remain trapped inside the unit and overheat. 

When the unit overheats, the heat pump will shut off before it reaches the heating cycle. 

You must change the filters every 3 to 4 months, based on the filter thickness, or whenever you see it dirty. 

Try checking the filter every month. 

Open the heat pump access cover and pull out the filter to check it. 

If it is very dirty, replace it with a new one. 

If the filter is reusable, wash it, dry it, and then put it back into the unit. 

While installing the filter, ensure the arrow direction remains the same as before. 

When you buy a filter, get the one that suits your heat pump’s size and model. 

4. Refrigerant leakage

Refrigerant helps in cooling or heating the air around you. 

The air absorbed by the heat pump passes through the coils, where the refrigerant removes the heat from the air and spreads it throughout the house.

It does the opposite thing with the air when you set the thermostat in HEATING mode with the help of the reversing valve. 

If the refrigerant starts leaking from your unit, the heat pump won’t work properly, leading to frequent short cycles. 

To confirm the problem, check for water puddles around your unit. 

Sometimes, you cannot identify the problem because the liquid is colorless, odorless, and fades after some time. 

Inhaling or touching the liquid is harmful. To understand the problem better, some manufacturers add a slight green tint.  

You need an HVAC expert to replace the refrigerant tube. 

5. Damaged compressor

The compressor helps circulate the air treated by the refrigerant throughout your house. 

It helps the heat pump to transfer heat and maintain the system’s rhythm.

If the compressor is faulty or damaged, the unit will short cycle and turn off before reaching the heating cycle.

You should call an HVAC expert to fix the compressor. 

Since compressors are quite expensive, think once before replacing them. 

If your unit is too old, buying a new unit would be better than changing the compressor. 

6. Faulty outdoor unit

The heat pump’s outdoor unit helps exchange the heat with the outside air. 

If the outdoor unit is defective, the exchange will get interrupted. 

As a result, your unit will shut down before completing the heating cycle. 

You need to call a professional to examine the unit and fix the problem. 

7. A problem with the control board

The control board is one of the main parts of the heat pump. 

It manages the functionality of your system. 

The control board controls the thermostat directly. 

If the control board has damaged, it won’t be able to read the temperature correctly and cause the unit to short cycle repeatedly.

Due to this, the heat pump will short cycle and shut down before the completion of the heating cycle. 

You have to replace the control board. 

Since it is a matter of electricity, you should hire an expert to deal with it. 

8. Poor insulation and leakage 

Insufficient insulation and leakage can make your heat pump short cycle frequently. 

The heat released through the heat pump will escape through the thin walls and leakages in the ducts, windows, and doors. 

The heat pump runs to maintain the room temperature consistently. 

But the warm air produced by the system will start escaping through these leakages. 

As a result, your unit will constantly short cycle while trying to maintain the temperature of the room.

Take a walk along the ducts to find the leakage. 

If you have insulated your house long ago, it is time to reinsulate it.

Call an HVAC to fix the leakages and reinsulate your house. 

Use caulk sealing to seal the cracks and openings in the doors and windows. 

If the window and door bases are empty, use weather stripping to seal those bases. 

Final thoughts

If you are a beginner facing short heat pump cycles, this article may help you detect the right cause and troubleshoot it.

Most of the problems will need an expert for troubleshooting. 

Still, you may fix some of them, for example, by correcting the thermostat settings and changing the dirty air filters. 

Keep an eye on the heating cycle running times and how frequently they run. 

The heating cycles should be 2 to 3 times per hour. Every time, it should run for 10 to 20 minutes. 

If the cycle stops before 10 to 20 minutes and the number of cycles is too frequent, call an HVAC. 

If you still need help figuring out the right cause, consider hiring a professional HVAC to look into the matter. 

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A house owner will face several issues with their heat pumps at some point. Some require professional help, while you can fix others on your own. A heat pump not running is a common complaint from most house owners. 

A heat pump does not run due to thermostat issues, tripped breakers, broken reversing valves or capacitors, frozen pumps, or leakages. Potential fixes include correcting the thermostat setting, resetting the breaker, defrosting the pump, and replacing the broken components.  

It is just a brief explanation. This article will explore all the reasons and how to troubleshoot them. If you cannot fix anything yourself, or hesitate to do it, hire a local HVAC professional team to examine the problems and solve them. 

Why is your heat pump not running?

A heat pump not running could indicate several issues. 

Electricity is one of them. 

A power outage won’t let your heat pump run. 

However, solving the issue is beyond your control. Wait until the power comes back.

Except for that, when a heat pump refuses to run, the problem is related to something else, for example:

• Thermostat related issues
• Power related issues
• Component and unit-related problems

You can solve some of them yourself, while others need professional help. 

Let’s explore these causes in detail. 

1. Thermostat issues

When winter arrives, check the thermostat settings before checking the outdoor unit. 

You need to change the setting from COOL to HEAT and then AUTO. 

When you set the temperature to HEAT, the heat pump will start releasing warm air throughout the house.

But if the setting is already in the HEAT option, but your unit does not respond correctly, there might be some other problem with your thermostat:

Incompatible thermostat 

The thermostat you use for your heat pump might be incompatible with your unit. 

All types of thermostats are not designed for heat pumps. 

Some good thermostat models for the heat pump would be:

• Google 3rd Generation Nest Thermostat
• Ecobee 4 Smart Thermostat 
• Honeywell RTH9585WF
• Emerson Sensi ST75

Dead batteries

If you use thermostats that rely on batteries, you must ensure that the batteries are good and fully charged. 

Faulty batteries will not let your heat pump run, and dead batteries won’t let the unit cooperate in the heating and cooling systems. 

Change the batteries when it runs low or malfunction. 

Most thermostats without a C-wire run by AA or AAA batteries. 

Wrong thermostat wiring

If the thermostat is not wired properly, the heat pump circuit will not receive the signal from the device to run.

As a result, your unit won’t run. 

Incorrect wiring can also fry the heat pump’s components and cause the pump to malfunction. 

Call a professional to check the wires in the thermostat. 

The thermostat is set to emergency heat mode.

When you set the thermostat to emergency heat mode, the system gets the signal to bypass the heat pump. 

The setting will fire up the auxiliary heat part and keep your house warm until your system is repaired. 

The system cuts off the signals to the heat pumps to keep running the electric or gas components.

When your thermostat is set to this setting, it will shut down the refrigeration system, the electric heating elements, and the outdoor fan motor. 

You must reset the normal operation’s thermostat setting to solve the problem. 

A quick thermostat check

To check the thermostat’s condition, perform a quick thermostat testing. 

The test includes setting the thermostat temperature to 5 degrees above or below the room temperature. 

After a few minutes, check the vents for cold or warm airflow. 

The thermostat should be okay if it is blowing warm air.

If not, call a professional to check the thermostat and the air handler. 

2. Power-related issues

Malfunctioning in the electrical systems is another cause behind a heat pump not running. 

 Besides power outages, power-related issues involve fuses and breakers. 

Power switches

Before going to the breakers, check the power switch first. 

All the heat pumps do not have power switches. But if your heat pump has one, ensure it is turned on. 

The switch should be in the cabinet near the air handler. 

Switch on the heat pump and wait for it to run. 

If the pump still does not run, check the emergency switches and turn them on. 

Tripped breakers and blown-up fuses

If your heat pump did not start running after turning on the power switches, it could be due to a tripped breaker or a blown-up fuse. 

If too many heavy appliances are connected to a circuit breaker, it will trip off. 

And if your heat pump is connected to one such circuit, it won’t start due to tripping. 

A heat pump is a heavy appliance, so the tripping may be due to the unit. 

For troubleshooting, you have to reset the breaker. 

To reset the breaker:

• Turn off the power and go to the breaker. 
• It will either be in the OFF position or at the center. 
• If the switch is at the center, flip it to the OFF position, wait for some minutes, and then turn it ON. 
• If the breaker is in the OFF position, flip it to the ON position. 

Call a professional to replace the fuse if there is a blown-up fuse. 

Make sure it matches the heat pump’s make and model. 

3. Component and unit-related issues

When your heat pump does not run and has no above issues, the problem could be in the components. 

The internal parts, like the compressor, capacitor, valves, condensate pumps, etc., are very important parts of the unit. 

If any part fails to do its job, the rest of the heat pump will start malfunctioning. 

So, it would be best to look into every component’s conditions. 

These parts will need experts for troubleshooting because there might be chances of replacement. 

Dead start capacitor

The start capacitor is responsible for kickstarting the heat pump by sending electrical signals to the motor.

If the capacitor is at fault or dead, it cannot send the signals to the motor. 

Hence, your heat pump will not run. 

You can confirm that the problem is in the capacitor if you hear clicking noises. 

Call your local HVAC team to fix the problem whenever you hear the noise. 

The capacitor may need replacement. 

Faulty reverse valve

The reverse valve ensures that the refrigerant flows in the proper direction. 

It switches the refrigerant direction and allows the heat pump to act as both heater and an air conditioner. 

The heat pump’s mode determines the flow of the refrigerant’s direction.

If the thermostat is set to release warm/cold air, but the heat pump produces the opposite one, the reverse valve is at fault. 

Hire a professional to replace the reversing valve. 

Time delay relay 

A time delay relay is a timer that keeps the current flow from running the coils constantly. 

The relay switch prevents your unit from short-cycling and keeps your heat pump from wearing out. 

If your unit is not starting, the problem might be in the time delay relay. Contact an HVAC to fix it. 

The heat pump switched to the defrost mode while running the heating mode.

It is common to see the outside unit filled with ice in winter. 

If the entire unit is filled with ice, it indicates a problem. 

To eliminate the frost from the heat pump, the unit shuts down the fan motor, turns on the heating elements, and turns the system into cooling mode. 

This confused setting mode in the heat pump will lead to a complete failure of the system. 

The ice in the coils will damage the fan blades and result in compressor failure. 

Call a professional to deal with the breakdown of the unit due to the confusing setting. 

Other causes

The above problems are some of the general issues your heat pump faces and refuses to turn on. 

Other than these, a heat pump not turning on would be due to weather conditions or leakage. 

Frozen heat pump

As I mentioned earlier, it is common for the heat pump to freeze in the winter. 

The heat pumps have a defrost mode setting which helps unfreeze the ice buildup. 

It should melt within 30 to 90 minutes. 

If it doesn’t, the heat pump will not run due to frozen coils and fans. 

It will lead to other issues, like compressor failure. 

Use hot water to defrost your unit. 

Call a professional to fix the unit. 

Avoid using any sharp objects to scrape the ice. 

Frozen evaporator coil and overflowed condensate pan

Check for leakage in the refrigerant lines. 

The leakage in the refrigerant lines will leak the liquid and keep your unit from heating. 

Low refrigerants will not let your evaporator coil have enough heat transfer. 

As a result, the coil will freeze. 

A frozen evaporator coil only happens when the heat pump is in cooling mode. 

The ice will melt and overflow in the drain pan. 

It will further trigger the float switch and stop your heat pump from running. 

Another reason is dirty filters.

The dirty air filters restrict adequate airflow. 

As a result, there won’t be enough heat to be transferred to the evaporator coil, leading to a frozen coil. 

Since the warm air will remain trapped inside the unit, the frozen coil will start melting and overflowing the drain pan. 

You must call a professional if the problem is a frozen coil. 

Clogged condensate drain line

A clogged drain line is another circumstance where the condensate pan overflows. 

The condensation caused by the heating system flows to the condensate pan and escapes through the drain line outside the house. 

If the line is clogged, the water will back up, come back into the unit, overflow the pan, and trigger the safety switch. 

As a result, the unit will shut down and prevent further running. 

The good news here is you can clean the drain line yourself. 

• Turn off the unit.
• Locate the condensate drain line. It will be a white PVC pipe located near the outdoor unit. 
• Find access to the line, pour 1/4th cup of vinegar into the line, and let the solution sit for 30 minutes. 
• After that, wash the line with normal water. Repeat every month. 

Another method is:

• Use a shop vac to create a strong connection between the drain line’s end and the shop vac. 
• Turn on the shop vac for 1-2 minutes and turn it off. 
• The drain line will be clear. 

Your heat pump should start working after some time. 

If it doesn’t, the clogging may be too high and extensive, or the problem is something else. You need professional help. 

Final thoughts

Check the thermostat settings and tripped breakers if your heat pump does not run. 

If everything is fine, move forward for other issues, like capacitors, reverse valves, frozen heat pump, evaporator coils, and clogged drain line. 

You can clean the clogged condensate lines yourself. 

But if the problem is too extensive or something else, call an HVAC to troubleshoot it. 

Regular yearly maintenance and servicing of the unit can prevent these problems and encourage smooth functioning. 

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Heat pumps are environment-friendly, cheap, and multipurpose units. They keep you warm in the winter and cool in the summer. A thin layer of ice in winter is normal, but a thick layer that doesn’t melt is serious. 

The heat pump freezes due to insufficient airflow, stuck reversing valve, defrost mode failure, dirty coils, low refrigerant, and filthy filters. To fix a frozen heat pump, find the frozen area, turn off the heat pump, and turn on the fan in the thermostat. 

It is frustrating when a heat pump freezes, but do not panic about the condition. This article will explain the primary reasons behind a frozen heat pump and how to unfreeze it.

Why does the heat pump freeze?

It is quite normal for the heat pump to freeze in winter. 

If a thin layer of ice disappears after 30 to 90 minutes, it is normal. 

The outdoor air contains vapor and changes to ice when the air is very cold. 

Heat pumps are prone to freezing during the cold snaps in winter. 

But, if the ice does not go away within 30 to 90 minutes, there are other problems, like defrost failure, low refrigerant, etc. 

You should not install the external unit in a place where water from the roof or gutters can fall on the unit. 

The heat exchanger contains a programmed defrost cycle that heats the condenser gas lines to melt off the ice. 

The system also has a temperature sensor on the condenser to provoke the defrost cycle during too much ice buildup. 

The sensor’s location is critical because it influences the defrost cycle to kick on. 

A heat pump can also freeze up in hot summers, but the problem will be serious. 

It is the time when you need the air conditioner to work at its best the most. 

So, summer is a terrible time for the heat pump to freeze and hinder the AC’s performance. 

Signs of a frozen heat pump:

• The inner coils of the furnace will freeze up in ice.
• The defrost cycle will fail to activate and work properly. 
• The air won’t be pulled into the air conditioning fins. 
• Your unit will have a poor heat output. You will feel colder than usual.
• The energy bill of your house will increase. 

A frozen heat pump indicates a serious issue, especially if the ice doesn’t melt within 30-90 minutes. 

If the ice buildup swells over time, the heat pump is freezing inside too. 

1. Defrost control board malfunctioned

The defrost control board is a part of your heat pump system. 

It controls the frequency of the heat pump going to the defrost mode. 

If the control board’s parts fail, the defrost cycle will not be able to unfreeze the pump. 

Common defrost issues include:

• Broken thermostat 
• Defrost timer issues
• Broken defrost relay

If you are facing a problem with your heat pump due to the defrost control board, you must hire a technician to look into the matter. 

The technician might have to replace the part of the defrost control board that is creating the freezing problem. 

2. Defrost mode failure

Besides the control board, other reasons can also hinder the defrost’s functioning. 

• Water dripping inside the unit can fail the defrost mode and build up ice in the heat pump. 
• If the heat pump fails to drain enough moisture, it will gather in your unit, turn into ice and freeze your pump. 
• A wrong installation can also freeze up your heat pump and fail the defrost mode, especially if the unit is placed in a tilted position or lower than the ground level.

Call an HVAC to fix the water buildup and inadequate drainage system. 

Ensure the unit is placed over a flat surface and not into the ground. The unit must remain straight. 

3. Reversing valve issue

Your system must reverse the refrigerant flow to defrost the heat pump. 

Instead of taking heat from the outside and carrying it inside, the heat pump will take the heat from the indoors and carry it to your outdoor unit. 

The reversing valve is a part of the heating system that determines the direction of the refrigerant flow. 

But, if the valve is broken or malfunctions, the refrigerant flow won’t reverse. 

As a result, the heat pump will have a frost buildup which might not melt. 

You will need a technician to deal with the problem. 

4. Low refrigerant 

The refrigerant is a fluid that absorbs the heat from the outside and carries it inside your house. 

If the heat pump runs out of refrigerant fluid, the heat pump cannot circulate enough air throughout the room, causing the pump to freeze. 

Since the refrigerant system is closed-loop, you might be unaware of the leakage and low refrigerant. 

Hire an HVAC expert to look into the refrigerant tank and fluid. 

They will examine for leaks, replace the tank, and refill the fluid. 

Be careful of the technicians who charge for refilling the tank without checking for leaks or repairing them.

5. Restricted airflow

When the airflow is restricted, the heat pump will not extract enough heat to keep the surrounding air comfortable. 

It will also cause a defrost cycle failure. 

Airflow is restricted due to the dirty filters, and they will prevent smooth airflow through the heat pump. 

Over time, the filters get dirty while trapping the dirt and debris in the air particles. 

So, check the filters once a month and change them every 3 to 4 months. 

Blockages can also happen if the dust and debris enter the heat pump and block the air vents. 

For example, twigs, fallen tree branches, pebbles, etc., can block the airflow in the condenser. 

Make sure to maintain a 2 to 3 feet distance between the unit and shrubs. 

6. Dirty evaporator coil

The evaporator coil absorbs the hot air from the surroundings and cools it with the help of the refrigerant liquid. 

Over time, the coil will become messy and won’t work efficiently as before. 

When it occurs, the heat pump will start freezing up. 

If you have dealt with such problems, you can encounter the problem yourself. 

Otherwise, you need an experienced HVAC expert to handle the situation. 

The coil needs to be cleared, requiring special kits and proper tools so that the fins and the coils do not bend. 

7. Faulty thermostat 

If the thermostat works incorrectly, it will freeze up the heat pump of your house. 

An incorrect thermostat sends wrong signals, for example, telling the evaporator to get too cold. 

As a result, your heat pump will freeze, no matter the season. 

It would be best to have an HVAC to deal with the matter. 

Another thermostat issue is when you set extremely low temperatures. 

If you have set a low temperature in your thermostat, the coil will get the signal for the same. 

When the condensation freezes, your heat pump will freeze, even if the weather is hot outside. 

An average temperature should be 65-70°F.

8. Excessive moisture around the heat pump 

When excessive moisture gathers around your heat pump, there could be chances of the heat pump freezing. 

Water buildup around the unit is caused due to a broken gutter.

Excessive moisture around the coils that remain uncollected in the drain will freeze inside your heat pump. 

You must ensure that no water gathers around the unit or the coil. 

You need an HVAC expert to fix the problem. 

9. Faulty blower motor

A faulty blower motor will fail to blow the air throughout your house. 

So, moisture can gather inside your unit, leading to a freezing heat pump over time, especially in winter. 

You need to hire an HVAC to resolve it. 

10. Dirty fan blades

When the fan blades of the blower are too filthy, it will restrict the airflow from the unit to your house and exhaust the unit. 

As a result, moisture can accumulate in the unit, especially around the coil. 

Due to the excessive moisture buildup, your heat pump will not drain this moisture and will turn into ice over time. 

Expect the situation to occur mostly in the winter.

Call an HVAC professional to solve the issue. 

11. Excessive cold air

Heat pumps can freeze if the weather is too cold to handle. 

The standard heat pumps can withstand up to 35 to 40°F, but below 35°F, the unit will get overwhelmed and freeze up. 

One of the common signs behind a heat pump freezing up is the condenser freeze-up. 

If the temperature outside is too low for the heat pump to tolerate, kicking the unit into defrost mode will fail. 

Even if the unit goes to defrost mode, it will have trouble melting the ice. 

You can only do something here once and when the weather becomes tolerable. 

12. Failed auxiliary heat

The heat pump gets overwhelmed when the winter arrives, and the temperature goes too low. 

The unit will activate a setting called auxiliary heat. 

It is a supplement heat source that runs on current.

It keeps you warm even when the heat pump fails to bring the heat inside your house.

The auxiliary heat kicks automatically. 

Once the temperature drops too low, the thermostat will signal the auxiliary heat to kick. 

Sometimes, the thermostat fails to kick the auxiliary heat, causing the heat pump to freeze. 

There is no solution to this. Wait for the temperature to come back to normal. 

13. Dripping water

Rain, snow, and water vapor can gather around your unit and ice up on the heat pump in the winter.

It is completely normal in winter. 

Besides, the heat pumps are designed to tolerate freezing temperatures. 

If your unit’s defrost mode is working fine, it should be able to melt the ice and keep your pump safe. 

If not, you need an HVAC to fix the defrost mode and resolve the freezing issue. 

14. Slab settling

Heat pumps are mostly placed over concrete slabs. 

Do not put the heat pump directly over the ground, as pests can enter your unit easily and cause malfunctioning. 

Though putting the unit over a slab is acceptable, a sinking slab can create issues like restricting the airflow or blocking the drainage system. 

As a result, the heat pump can freeze up. 

Leveling the sinking slab with a longboard should prevent the heat pump from freezing. 

15. Problems with the compressor 

The compressor is the heart of the heat pump that helps the refrigerant liquid to travel through the system and change the pressure. 

If the unit cannot extract the heat due to a faulty compressor, the heat pump will freeze and fail to operate well. 

A motor failure will develop issues in the compressor. 

If the motor has failed, you won’t hear the compressor after turning on the unit. 

Over time, a compressor can wear out, especially due to dirt buildup or poor maintenance. 

Another reason behind a bad compressor is its bearings and contacts. They will also wear out over time. 

You need an HVAC’s help to fix the compressor issues. 

How to prevent the heat pump from freezing in the winter?

Unfortunately, you cannot do much when the heat pump freezes in the winter. 

Unless and until the temperature returns to normal, you cannot unfreeze the heat pump. 

Some problems will also require an HVAC’s attention.

However, you can follow some tips to prevent or lower the chances of the heat pump freezing up:

Clean the air filters

You must change the air filters every 3 to 4 months. 

However, the changing frequency depends on the filter thickness, for example:

• Change a 1 to 2-inch filter every 1 to 3 months
• Change a 2 to 3-inch thick filter every 3 to 6 months
• Change a 5 to 6-inch filter every 9 to 12 months.

If your filter is washable and reusable, you can take out the filter, wash it, and put it back into the heat pump instead of replacing it. 

The arrow directions should be the same as before.

Make sure the vents are open.

If your heat pump is ducted, keep the distance between the ducts and your furniture or other objects at least 10 inches for adequate airflow. 

If the airflow gets blocked due to the closed or blocked ducts, your heat pumps will freeze. 

Some house owners purposely block a few vents when they are not in use to save energy bills. 

But that is a bad decision.

It increases the air pressure to other open vents, leading to other damages. 

Relevel the heat pump slab.

Work a longboard under one end of the slab, lift it, and put adequate sand under it. 

Do the same for the other end of the slab. 

You can also replace the slab with a plastic pad. 

It should level the slab under the heat pump. Place the heat pump straight and not slanted.

The refrigerant will travel smoothly without interruption when the heat pump stays over a leveled slab. 

Remove debris from the heat pump.

Wear and mow the area around the heat pump to avoid debris buildup around the unit. 

Clear the snow and moisture buildup and clean the dirt with a garden hose. 

Avoid putting the heat pump in areas where water from the gutter and roof can fall over the unit. 

Ensure regular maintenance

Regularly checking the unit’s condition and having annual maintenance and servicing will ensure the unit’s best working condition. 

Before the winter season strikes your area, call an HVAC expert for a thorough inspection of the unit to ensure the optimum functionality of the furnace components. 

Confirm that all the parts are in good shape, from the fans to the vents. 

Keep a close eye during the winter.

During the winter, keep a close eye on your unit. 

Since the temperature can drop lower than normal, there could be higher chances of freezing up. 

Walk around the outdoor condenser every 1-2 days to check for any airflow blockage and freezing. 

Ensure that the ice layer dissipates after some time and does not layer up too thick. 

If the ice thickness increases too much and does not vanish within 2-3 days, check for other issues described above. 

Immediately, call an HVAC expert to look into the matter. 

Final thoughts

A frozen heat pump can cause several issues. 

Heat pump freezing in the winter is normal due to the low temperatures. 

Besides, the heat pump has a defrost cycle mode that should defrost the ice buildup. 

So, the ice buildup will melt within 30 to 90 minutes. 

If the ice does not melt within this time, the defrost cycle is at fault, or there are other issues. 

So, hire a professional to resolve the frozen heat pump. 

Also read: 12 Reasons Your Heat Pump Is Running Constantly (+Fix)

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As a heat pump owner, you might have been used to the normal noises the unit releases. Extra noises from the unit are its way of complaining about serious issues. So, when your ear perks up at the heat pump’s constant noise, it is time to examine the problem. 

The major reasons behind a heat pump constantly running are an oversized unit, dirty air filters, cold weather, and wrong thermostat settings. Buying the right unit size, changing the filters, and correcting the thermostat setting should troubleshoot the problem. Cold weather is beyond control.

Besides these, there are numerous other reasons behind a heat pump constantly running, and this guide will cover all the points in detail. So, stick to the article till the end to explore the reasons and troubleshooting steps. 

How long should a heat pump run?

A heat pump is a unit that heats your room by transferring thermal energy from the outside with the help of a refrigeration cycle. 

Some heat pumps can also do the opposite by removing the heat from your room and cooling it.

A heat pump usually has 2 to 3 cycles per hour. 

The unit will run for 10 to 20 minutes during the ongoing cycle. 

It is enough for the heat pump to provide adequate energy throughout your house. 

When your heat pump gives you the desired temperature, it should shut off its heating cycle. 

Is it normal for the heat pump to run constantly?

A heat pump generally should not run continuously. 

Once it has reached its desired temperature, the heating cycle should shut down. 

If it doesn’t, the constant running signifies something is seriously wrong with the unit. 

However, it is common for the unit to keep running in the winter. 

Since the weather sometimes gets too cold, the heat pump will try to give you warm temperatures by running over time. 

It happens when the outside temperature goes beyond 30 to 40°F. 

So, do not worry if the unit constantly runs in the winter season. 

But, if the heat pump continually runs when the temperature is average or high, it indicates a problem.

You need to inspect it and call a professional if needed. 

Let’s learn the reasons behind the problem. 

1. Undersized heat pump size

Different house sizes will require different sizes of heat pumps. 

If the pump is smaller compared to what is needed by your house, the unit will not be able to give you sufficient warm air. 

As a result, the unit will keep running until it gives you the preferred temperature. 

In the winter, the unit will struggle more and end up overheating. 

You must buy the right heat pump size for your house. 

A suitable-sized heat pump will determine your house’s level of heat loss based on your house insulation and give the required temperature. 

What should I do?

If you have an undersized heat pump, you should exchange it and get the right size. 

Please do not go for an oversized heat pump, as it will quickly heat your house and cause short cycles. 

2. Wrong thermostat setting

Thermostat issues are numerous, for example:

• Wrong thermostat setting
• extreme temperature setting
• Wire issues
• Dead batteries 

Correct the fan setting

Generally, the thermostat setting for the heat pump should be set to HEAT or COOL, based on the outside temperature. 

The thermostat setting should be AUTO. 

It will signal the thermostat to turn off the heat pump once the heating cycle is over. 

The heat pump will constantly run without stopping if the fan is set to ON instead of AUTO. 

The solution is simple. Change the setting to AUTO. 

Set up a suitable temperature in the thermostat. 

Another problem with the thermostat is the temperature setting. 

Setting the thermostat to extreme temperatures will make your unit run continuously over time. 

For example, your heat pump will keep running and struggle to give you a temperature of around 77°F in the winter or 62°F in the summer. 

Check the thermostat and set the temperature to a suitable level, for example, between 65 and 75°F throughout the year. 

Check the wiring

The heat pump turns off when the thermostat sends a signal to the unit to deactivate the heating cycle. 

The unit will keep running if it does not receive the signal for shutting down. 

The reason could be frayed wires. 

The best solution is to isolate the circuit and remove the faceplate to check the thermostat wiring. 

If you find anything wrong, call an electrician to fix the wires. 

Replace the dead batteries.

Like the wire issues, a dead or low battery does not allow the thermostat to signal the heat pump to stop the cycle. 

As a result, the unit will keep running until it receives the signal from the thermostat. 

Thermostats without C-wires run by AA or AAA batteries. 

When they run low, the thermostat lacks the power to call off the heating system. 

Replace the batteries once a year to prevent the problem. 

3. Refrigerant leak

The refrigerant in the heat pump absorbs the heat from the surrounding air and releases cold air in the summer. 

It does the opposite in the winter with the help of the reversing valve. 

If the refrigerant liquid is leaking from the tube, you won’t be able to receive enough hot or cold air. 

So, the heat pump will constantly run and struggle to give you enough warm air without stopping the cycle. 

The leakage is caused due to rust, erosion, and cracks. 

What should I do?

Confirm the problem by looking around the unit for water droplets.

If you suspect refrigerant leakage in your heat pump, contact a professional HVAC team to replace the refrigerant tank.

Make sure that experts remove the tank first, replace it with a new one, and then refill it.

If they only refill the line, you will again face leakage issues. 

4. Dirty heat pump 

A clean heat pump will run more efficiently than the dirty one. 

Over time, dirt and debris can accumulate in the coils and air filters and restrict adequate airflow. 

Due to the clogged filters, the air cannot pass through and distribute around the house. 

As a result, the unit struggles to circulate the warm air and constantly runs until it provides you with the desired temperature. 

The airflow will also flow through the coils to circulate evenly all over the house. 

But dirt and debris will lower its capacity and reduce the unit’s efficiency. 

How do I clean the unit?

You must clean or change the air filters every 3 to 4 months. 

The changing time will increase or decrease based on the filter thickness. 

The thinner filters will need more frequent changing than the thicker ones. 

Check the filter every month to determine the dirt level. 

Some parts of the heat pump cannot be accessed without an expert’s help, for example, the evaporator coils. 

For such areas, you need a local HVAC team for help. 

5. Blocked air heat exchangers 

Since the heat pump is an essential part of the HVAC system, you should ensure its smooth functioning.

If you have an air source heat pump, enough air gets drawn across the heat exchanger to provide enough energy to the heat pump for heating the house. 

If the unit runs without ending the heating cycle, the reason would be blocked outdoor airflow. 

Over time, the heat exchangers will get clogged with leaves, dirt, and debris. 

As a result, the heat pump faces difficulty in working properly.

So, the unit will keep struggling and continue running until your house receives enough warm air. 

How to troubleshoot the problem?

You can check the heat exchanger yourself and remove the leaves and other dirt materials from it. 

The step should be a part of the annual maintenance and servicing. 

So, you do not have to do it if you have hired an HVAC team for the annual maintenance.

Besides regular annual maintenance, clean the surrounding area of the outdoor unit after yard work or strong weather. 

6. Frozen unit

In the winter, it is common for the heat pump’s outdoor unit to have ice buildup.

However, the unit has a default defrost cycle that helps melt the ice buildup from the heat pump. 

Due to the blockage and ice accumulation, it can block the airflow and make your unit run longer than it normally runs. 

Solution

There is no proper solution to this problem. 

You must wait for the temperature to become normal or let the defrost cycle do its job. 

You can melt the ice using the garden hose or warm water. 

Avoid scraping the unit with any sharp objects. 

7. Open or cracked doors and windows

If your house has many open windows and doors, your heat pump won’t be able to give you a comfortable temperature. 

In the winter, the cold air will enter your house through the open doors and windows, and the warm air will escape. 

As a result, your house will remain cold, no matter how hard it tries to give you a comfortable temperature. 

But, to give you the right temperature, the unit will work hard and keep running.

How to fix the problem?

When you turn on your unit, ensure the doors and windows are properly closed. 

If cracks or open bases exist, seal those areas. 

You can use weather stripping to seal the base of the windows and doors. 

The stripping will block the outside air and keep the dirt and debris from entering your house.

8. Poor or leaky insulation

Over time, the insulation of your house will weaken and become thin.

As a result, the cold outside air will enter your room easily.

Since the thin walls cannot stop the cold air from entering your house, the warm air provided by the heat pump won’t be sufficient. 

So, to keep your house warm and give the desired temperature, the unit will keep running.

The same happens if there are insulation leaks. 

The warm/cold air provided by the heat pump will escape through the leaks, and your house won’t get the desired temperature. 

So, the heat pump will constantly run to give you a comfortable temperature.

What should I do?

Make sure that your house is well-insulated. 

If you already insulated your house years ago, you should re-insulate. The insulation weakens over time. 

Call a professional to re-insulate your house and seal the leakages. 

9. The blower relay switch malfunctioned.

The blower relay switch controls the thermostat and heat pump communication. 

If the blower relay switch’s controller is malfunctioning, it will not let the thermostat communicate with the heat pump. 

As a result, the thermostat cannot signal the unit to stop, and the fan will keep running even if the heat pump is turned off. 

Solution

Try turning off the fan at the thermostat. 

If it does not work, you must replace the blower relay switch. 

Call a professional to replace the controller. 

10. Emergency heat activated

The thermostat has an emergency heat setting. 

Turning it on will bypass the primary heat pump source and turn on the auxiliary heat part to keep running until your house receives enough warm air. 

The problem will get coupled with a defrost cycle, making your unit run constantly. 

Solution

Check the thermostat setting. 

If you have activated the emergency heat or EM heat switch, reset your thermostat for normal operation. 

Call a professional if you cannot deal with it. 

11. Damaged compressor contactor

The contactor controls the electricity flow to the heat pump’s internal components. 

When the contactor is at fault, the heat pump cannot receive the electricity to give you the desired temperature. 

As a result, the unit will constantly run to give you warm air, but in vain. 

What to do with the contractor?

The contactor will need replacement. 

Call a professional for the replacement.

12. Stuck reversing valve

The heat pumps can be useful for both heating and cooling systems. 

It contains a reversing valve that switches between the heating and cooling systems whenever required. 

If the valve gets stuck, the heat pump will not reach the preferred temperature and keep running without any breaks. 

How can I fix the valve?

You need a professional to fix the problem. 

Check whether the vents’ air is hot or cold to confirm the problem.

If the air is cold but the thermostat setting is high, arrange for a professional inspection. 

Things to do before calling an HVAC expert

Before you call an expert, you should perform certain things when your heat pump constantly runs. 

All the problems won’t require an expert’s attention. Solving some of them yourself can save you time and money. 

• Check the thermostat setting for your heat pump. It should be in the AUTO position, and the temperature must be average, neither too high nor too low. 
• Check the outdoor unit, i.e., the heat exchanger. Consider cleaning the surrounding areas to clear the airflow blockage. 
• Change the filters every 3 to 4 months. 

There are numerous reasons behind a heat pump running constantly.

Reasons like undersized units, dirty filters, wrong thermostat settings, drafty rooms, and blocked air heat exchangers are common and easy to fix. 

Others, like damaged contactors, stuck reversing valves, dirty coils, poor insulation, malfunctioning relay switch, and refrigerant leak, will need the HVAC’s attention. 

Regular annual maintenance and servicing of the unit can prevent the above issues and encourage the smooth functioning of the unit. 

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