12 Reasons Your Thermostat Is Blank+Fix

A thermostat is important as it controls the house’s temperature and comforts the house members. Being the main line of communication of the heating and cooling system, you must fix it as soon as it goes blank. Finding the main cause behind it can help in quick fixation. 

The reasons behind a blank thermostat could be dead batteries, tripped breaker or safety switch, loose wire connections, a broken thermostat, a dirty air filter, a blown-up fuse, mismatched parts, or an open furnace door. Sometimes, your thermostat either has low brightness or is switched off.

Since there are so many reasons behind the issue, you must find out the real cause behind a blank thermostat and fix the right issue. This guide will share all the reasons in detail and how to fix the problem. 

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My thermostat is blank: What should I know?

You suddenly watch your thermostat going blank during a cold winter morning. 

Since your thermostat is the most important thing every season, it is important to find out the real cause behind the blank thermostat and solve it soon. 

The problem could be a minor one, but it could be a major one too. 

It would be best not to take any chances unless you detect what is wrong with it. 

The standard non-programmable thermostats like the Honeywell and Trane thermostats have no such issues other than their batteries and dust accumulation. 

These thermostats are the least expensive and least energy-efficient models. 

When you change the house’s temperature, you must go back and forth to readjust it. 

Programmable thermostats like the Bosch, Google, and Ecobee often have other issues than the batteries, for example, using too much power or a tripped circuit breaker.

Some thermostats do not send any notifications when the power is off. 

It is an important problem because you need the proper notification to understand emergencies. 

Since these programmable thermostats come with multiple features, they extend the life of your heating and cooling system and save up to 30% of energy. 

That is why a thermostat getting blank is quite a big issue. 

Smart thermostats learn the behavioral patterns of your house and work accordingly. 

They notify you of the weather conditions and major issues in the HVAC system. 

WiFi allows you to control these units with your mobile phones, computers, and tablets. 

The common issues related to a blank thermostat could be:

  • The thermostat is going blank and again coming back. 
  • The thermostat is going blank, but the fan is working. 
  • The WiFi thermostat is going completely blank. 

Do not panic when your thermostat behaves abnormally, as you have covered with the tips to solve them. 

You can troubleshoot some problems yourself with simple steps. 

Let’s get into the reasons and the solutions right away. 

1. Dead batteries

One of the main reasons behind a blank thermostat is its batteries. 

Maybe the batteries have died, so your thermostat stopped working and went blank. 

A thermostat battery can last up to 5 years. 

So, you have to replace the batteries before that. 


If you know that the batteries have died and that is the only reason behind the blank thermostat, replace the batteries. 

Battery replacement difficulty will depend on the feature and model of the thermostat. 

However, batteries compatible with your thermostats are easily accessible in most cases. 

Take the thermostat out, remove the cover, slide out the battery compartment, and replace the old batteries with the new ones.

Check the battery polarity before you keep the battery compartment back. 

2. Tripped circuit breaker

You may have installed the thermostat in the breaker that supports another powerful device. 

In that case, both appliances will draw a surplus of power, resulting in the breaker tripping because the breaker won’t handle so much power. 

Once the breaker trips, your thermostat will turn off, and the screen will go blank.

Consider checking the circuit breaker if the problem is not with the battery. 

If it has tripped, you need to reset the breaker.


If this is your first time resetting a breaker, check for three settings, ‘On,’ ‘Off,’ and a middle neutral setting. 

When the breaker trips, it will be in the center’s neutral setting.

You must flip the switch to ‘Off’ and then ‘On’ to reset the breaker. 

3. Triggered safety switch 

Some thermostats or HVAC systems have a safety switch that gets activated when it senses a threat in the air conditioning or furnace due to some defect. 

It could be a frozen evaporator coil, excess condensation, high moisture level, or high temperature inside the house.

If anything of that sort occurs, the safety switch will get alarmed. 

It will alert your thermostat to shut off, causing a blank screen. 

If your thermostat has a safety switch, see if it got triggered. 

If it got triggered, check for some reason behind the triggering of the switch. 


Contact an HVAC professional to find out the real cause behind the tripping off of the safety switch. 

Switch the thermostat to a different setting, for instance, any external button.

4. Loose connections

Sometimes the thermostat will face some wire issues, preventing the device from getting enough electricity for operation.

A thermostat has various wire connections that serve different purposes, for example, screen display, device communication program, etc. 

If any of these connections get loose or the wire has some issues, the thermostat will not work and go blank.


Call the professional HVAC team to fix the wire problems if you suspect such a thing. 

You should only approach these problems yourself if you have an electrical background. 

Also read: How To Add C Wire To Thermostat?

5. Open the furnace door

If you have a Honeywell thermostat, the blank screen on the device indicates that the furnace door or the air conditioning door is partially open by mistake. 

These thermostats are programmable and turn their screen off when the furnace or air conditioning door remains open. 

A low-voltage transformer in the HVAC systems provides power to the thermostat. 

If the furnace is off, so will the thermostat. 

If the door is half open, the thermostat will trigger the safety switch and turn off the furnace and the thermostat. 

In that case, the device screen will be blank.

The same is the case for the AC door.


To correct the issue, see whether the furnace door is closed.

If the door is closed, ensure the furnace is flipped in the ‘on’ position. 

6. Blown fuse

If the fuse of your HVAC system has blown off, the thermostat will stop working and show a blank screen. 

Use a multimeter and reach the AC condenser unit to check the fuse. 

You will find the fuse near the exterior wall of the house. 

Search for the fuse and see if the filament or the u-shaped wire is broken. 

Connect it with the multimeter to check for any leftover voltage. 

If there isn’t any, you need a new one. 


You have to replace the blown-up fuse with a new one. 

Since it requires electrical experience, you cannot do it yourself unless you have an electrical background. 

It is best to leave it in the hands of the HVAC professional team. 

Once you have replaced the fuse, the thermostat screen should light up within 2 hours.

You need to use the exact type of fuse as the old one. 

If there is a mismatch, your thermostat will still be blank.

7. Dirty air filter

The air filter will become dirty over time. 

It further clogs the AC’s air filter and makes it shut off. 

The safety airflow switch in the indoor unit will get triggered if you do not change it in time. 

The thermostat will shut off if the switch gets tripped, causing a blank screen. 


Check the air filter. 

Replace the filter if it is very dirty and clogged. 

To avoid such problems, replace the air filter every 1-3 months. 

To replace the filter:

  • Turn off the AC.
  • Remove the front cover. 
  • Take out the filter and shake it to dislodge the dirt. If the dirt is too much, you can either clean it with soapy water or buy a new one. 
  • Cover the AC with screws, if any. 

While replacing it with a new one, ensure it matches the unit. 

8. Dirty wiring

Thermostat wires will get accumulated with dirt over time. 

Even a wireless thermostat has wires that will clog dirt. 

The clogged dirt will create problems turning on the thermostat and thus result in a blank screen. 


You must clean the dirt to turn on the thermostat. 

To clean the wires, turn off the circuit first to remain safe. 

Then, remove the thermostat cover, and see if you find any clogged dust. 

If there is a lot of dirt, clean it off with a brush carefully and sweep them off the wires. 

9. Mismatched parts

Parts of some indoor or outdoor units will sometimes require replacement when they stop working or degrade. 

So, when you get new parts for replacement, you need to ensure that the parts are the same structure and model as the old ones. 

If not, your thermostat will not start working and will remain blank like before. 

For example, suppose you have bought any part of the air conditioner that mismatches the device. 

In that case, the thermostat won’t show any reading and will remain blank. 


You need to change the incompatible part and get the one that matches the unit. 

Find something like the one that you have used since the beginning.

If you are unsure about the situation, you can call the experts to deal with it.

10. Thermostat is closed

Sometimes, it is very silly to expect the thermostat to show readings without checking whether it is turned on. 

In that case, obviously, your thermostat will remain blank. 

Another condition is a power outage. Maybe there is load shedding, and you did not realize it.


Before you look for any problem and troubleshoot it, check that you have turned on the thermostat properly. 

Someone may have accidentally switched off the device and forgotten to turn it back. 

Check for the power outage too. 

If the power and switch are on, and the thermostat is still blank, you only start finding the cause and troubleshooting it. 

11. The thermostat has low display brightness.

You have turned on the switch, and there is no power outage, but you still see the thermostat screen blank. 

Check if the brightness level is too low or not. 

You have decreased the level and forgot to increase it in the morning. 

That is why you are seeing it blank. 

Some thermostats also adjust their screen brightness on their own. 

When the light is too much in the surrounding area, the brightness level reduces to save battery power.


Check the brightness level and increase it if it is very low. 

If the thermostat has adjusted itself, check if the brightness is too low before you check other potential issues.

12. Thermostat needs a replacement

At some point, the thermostat will reach a point where it will need replacement. 

A thermostat will last around 10 years. 

If your thermostat is that old, it has reached a decade and has a bit of dust too. 

 In that case, the thermostat will not give any notifications or readings. Instead, it will go blank. 


If your thermostat has been over a decade, it is time to replace it with a new one. 

You can get a lot of good options, like Ecobee, Emerson Sensi, Google, etc. Hire a professional to know the best one for your house. 

What should I do if I cannot solve the problem myself?

Out of all these reasons, there are some points where you can troubleshoot the problem yourselves. 

As for the other points, you need professional skills and electrical background. 

You need to be responsible while taking an approach to any solution. 

The best option is to hire a professional team. 

The trained experts will tell you the exact problem without wasting time, especially when the safety switch triggers or trips off, and fix the problem carefully. 

They will also ensure that the thermostat has started successfully and there is no other problem. 

The experts will also suggest you hire an electrician if there is a problem with the wiring. 

Consulting an expert may be costly, but it is worth it. 

An expert can tell you the real cause, fix the right one, and prevent expensive damages. 

Final thoughts

You are here means you have learned all the reasons behind a blank thermostat. 

Though there are many reasons behind it, you must find out the real cause before approaching the solution. 

Otherwise, you will end up diagnosing and troubleshooting the wrong cause. 

That will lead to expensive damages. 

That is why experts recommend hiring a professional to deal with the work. 

Some problems like replacing dead batteries, tripped breakers, a turned-off thermostat, low brightness, etc., can be easily worked out. 

But others, like wire issues, incompatible parts, triggered safety switches, blown-up fuse, and thermostat replacement need experts’ suggestions. 

You can work if you have the proper experience, but it is better to consult a licensed HVAC team.

So, be careful while dealing with the problems. 

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Arthur Smith

Howdy! I am Arthur Smith, an electrical engineer who is extremely passionate about electronics. I have lived in different parts of the US and currently reside in Wisconsin. I am one of those rare children who knew what he wanted to study and do in life right from the start. I was a curious child who wanted to know how switches work and how the AC works, and I would always observe my dad whenever he would handle the wires and fix things around the house. I currently work as an electrical engineer at a reputed company and write for this blog. And I read loads of books or play video games in my free time.

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