Honeywell Thermostat Backlight Not Working – Fix It Quickly

There are various benefits that Honeywell thermostat users enjoy, especially its display that can tell you the exact mode you are. Besides, it is very easy to know the temperature of your home. Sometimes, you may even use the thermostat as a clock since it is bright and reading it isn’t a problem.

All these goodies can be taken away if your Honeywell thermostat backlight fails to work. You may be eagerly waiting to set the device, but the screen goes blank. This complication is devastating since your comfort will be ruined and you may be forced to spend a lot of time configuring it. There are a few culprits like dead batteries, faulty wiring, blown fuse, slipped circuit breaker, flipped HVAC safety switch, or the door of your furnace is open.

Fortunately, all the above mentioned issues can no longer be a threat to your thermostat. I say so because they are fixable with the help of our guide. We will comprehensively discuss the causes of Honeywell thermostat backlight not working. In addition, we will equip you with an ultimate guide to solve the issue.

Quick table:

Ultimate guide on how to fix Honeywell thermostat not workingFunctionEssential tools
Replace dead batteriesTo rule out low-battery issueA new Honeywell thermostat battery
Rest your Honeywell thermostatTo correct broken or loose connection 
Replace a blown fuseTo restore the performance of the gadgetReplacement fuse
Flip circuit breaker back    To put the breaker into its correct posture 
Flip HVAC safety switch backTo enhance power flow
Step 6: Close the furnace door To alert the sensor 
Step 7: Replace the thermostatTo avoid regular repairHoneywell thermostat replacement

Reasons for Honeywell thermostat backlight not working

honeywell thermostat backlight not working

The causes of a problematic Honeywell thermostat are fully discussed below. Have a look at them to determine what exactly is affecting your device.

1. Dead batteries

Like any other electronic device Honeywell thermostat depends on a power supply to operate. There are two types of thermostats based on the power source i.e., battery-powered and C-wire ones.  Batteries are the common source of power for them, meaning that if they are dead, the device backlight won’t work.

No electric current will be transmitted to the device if the batteries are dead. Therefore, you should try checking the battery condition and make sure this problem is sorted.

2. Problematic wiring

Another reason for a black Honeywell thermostat backlight is the defective wiring. This issue occurs, mostly when the wirings are loose. Again, installing the thermostat without the C-wire may result in this complication. The device’s display will of course get defective because the current will not be fully transmitted to the unit.

3. A blown fuse

Here is another culprit that we can hold responsible for a Honeywell thermostat backlight not working. The Honeywell thermostat fuse may be blown due to a power surge. With such an issue, no matter how hard you try to press the device’s power button, the screen won’t turn on.

4. Reversed circuit breaker

Your thermostat backlight is likely to fail to turn on if the circuit breaker is tripped. Yes, this issue emanates from power surges, posing a challenge to the normal performance of your Honeywell thermostat. There is a simple trick that you can take to have this issue solved; no need to worry about it.

5. Flipped HVAC safety switch

HVAC systems come with a handy switch that always ensures your device is safe. However, these components might be defective, taking in wrong warnings. Such signals will cut off power flow to your Honeywell thermostat. Therefore, the display or backlight won’t turn on; because there is no power.

You should be in a good position to confirm that there’s nothing bad with the HVAC unit with you. Since this is a unit, any complication in a certain attachment may trigger a malfunction to the thermostat; and that’s the “no power issue”.

6. Furnace door is open

If the door of your furnace is open or loosely closed, the backlight will automatically stop working. There are different models of Honeywell thermostats and some of them are more sensitive to such an issue compared to others. If this is the problem, the display of the device won’t turn on.

Ultimate guide on how to fix Honeywell thermostat not working

There are various methods that you can put into practice to make your thermostat’s backlight work again. Have a look at them;

Step 1: Replace dead batteries

Ultimate guide on how to fix Honeywell thermostat not working

If you own a battery-powered Honeywell thermostat, opting for battery replacement can be the best solution. This should be the first action to attempt before you even think of searching for other issues. Dead batteries will probably make the display to go blank or become unresponsive.

There are different battery models in the market that you can opt for, but you should be careful not to bag home the wrong one. This means that you should consider buying a compatible Honeywell thermostat battery. This will help you to easily fix dead battery problems.

There are some occasions where the thermostat backlight is still blank even after replacing the batteries. If this is what you are going through, don’t worry because there are other troubleshooting methods; just advance to the next step.

Step 2: Reset your Honeywell thermostat

Resetting the thermostat is always advisable to correct broken or loose connections. Since loose wires are among the causes of a blank backlight/display, resetting the circuit breaker will do wonders. This method is very simple, especially if your Honeywell thermostat was installed without the c-wire.

To achieve this, you are urged to start by removing the batteries from the thermostat bay for some minutes. Install them in an opposite posture and give it something like 15 seconds before normal insertion. The magic may work for you; that’s if you are lucky. If your thermostat is not battery-powered, there is a handy “Restore to factory defaults” option that should fix the issue.

Try out this action and see whether the problem is persistent or solved; I say so because it might not work for all Honeywell thermostats.  If the thermostat backlight still doesn’t work, try another method. Therefore, don’t hesitate to move to another step.

Step 3: Replace a blown fuse

There is nothing else you can do to a blown fuse than opting for a replacement. These components are prone to power surges, meaning that if they are blown; replacing them will restore the performance of the gadget.

While searching for a suitable replacement fuse, the user manual should guide you. Read the specifications of the current fuse and trek to the market. It’s simple to replace since you can do it by yourself; or you can seek the help of a trustworthy expert.

Step 4: Flip circuit breaker back

Flip circuit breaker back

Power surges may reverse the HVAC circuit breaker, but thank God you can correct this manually and easily. Solving the issue involves a simple trick which is putting the breaker into its correct posture. Flipping it back will aid in restoring everything to normalcy. However, you should not worry because this problem occurs rarely.

But, in situations where the issue keeps on recurring, there might be something not good with the HVAC unit. Here a professional should help; but you should opt for the one who installed the system or a trusted one. Else, you may land on someone who will end up worsening the situation of your Honeywell thermostat.

Step 5: Flip HVAC safety switch back

This step is very simple since you only have to confirm there’s nothing complicated with the HVAC unit. After doing so, the next action will be to flip the safety switch back. Everything will come back to normal including the backlight of your Honeywell thermostat.

If the problem becomes persistent, then I would urge you to consult an expert to help you for the hassle. However, you may opt for other troubleshooting method in this article.

Step 6: Close the furnace door

After confirming that the door of your furnace is open, the deal is very simple. How about closing the furnace door? But, it should be tight. This is essential mostly to those thermostats that are more responsive to open doors. Luckily, shutting the furnace door will easily solve this.

Step 7: Replace the thermostat

Replacing your thermostat might be another reliable method to eradicate the blank backlight of your Honeywell thermostat. If the one has served you for many years, replacing it is inevitable. Old ones tend to encounter challenges with air conditioners or heating pumps. Yes, and this may result in a backlight going blank problem.

Replacing the device is necessary if you don’t wish to experience other hassles; it also prevents regular repair.

You might be interested to read also our another comprehensive article of: Why My Thermostat Clicks but Nothing Happens?

Frequently asked questions:

  • How long can a Honeywell thermostat last?

Under normal circumstances, a high-quality Honeywell thermostat may serve you up to 15 years. However, sometimes it may start misbehaving and this means you have to change it.

  • Can I override my thermostat?

Yes it is possible to override it by simple steps. Go to “settings”, “Preferences” and choose the “Smart Response Technology”. The next thing will be to turn off the ‘Recovery Mode’.


From the above content, you can realize that there are various factors that can lead to Honeywell thermostat backlight not working. Luckily, all these issues can be solved with the aid of the above complete guide. Subjecting your thermostat to great care is always necessary to enhance its lifespan. Make use of our article to restore the normal functioning of your Honeywell thermostat. 

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