When you notice that the temperature in your home is not as comfortable as always, your first reaction usually is to go to your thermostat and adjust the temperature. But this time, you’ve discovered your Honeywell thermostat’s display screen is blank, and you feel you’ve lost control over your HVAC system. You want to fix the problem as soon as possible, but you don’t know whether you’ll be able to troubleshoot and fix the problem yourself.
Fixing your Honeywell’s blank thermostat screen is easy to do yourself, and rectifying the issues can be as easy as replacing the batteries, reconnecting a loose wire, or adjusting the screen’s brightness.
In this article, I’ll look at possible causes of a blank Honeywell thermostat display screen, indicate how you can diagnose the issues, and provide general tips on how to fix them.
Step 1: Check whether the display screen is really not working
Most touchscreen Honeywell thermostat models have display screens whose brightness levels can be adjusted. And just like a smartphone, the thermostat’s screen can seem blank if the brightness level is set very low. This is especially true if you look at the thermostat’s display screen from a distance or in bright light.
Thus, the very first troubleshooting step you have to take is to verify whether the display screen of your Honeywell thermostat is actually blank, in other words, not working, or whether it just seems to be blank. A lot of time can be wasted on other troubleshooting procedures, while the problem could have been solved with a simple brightness setting.
How to check whether it is a brightness setting issue
Honeywell thermostats allow you to dim their screens to the brightness level you prefer. If you set the level very low, it might look blank if you don’t look carefully. But the thermostats are designed to default to full brightness when you touch the screen or buttons. So, when you detect that the thermostat’s screen is blank, touch the screen. If the display doesn’t brighten up, it is a sign that the thermostat is not working and you’ll have to troubleshoot further.
How to set the brightness level
If the display does brighten up, I recommend setting the brightness level higher so that you can always read the display, even in bright light and from a distance. To do that, touch “Menu” and then touch the “>” arrow until the word “Brightness” appears. Then touch “Select” and use the “+“ icon to increase the brightness. As the final step, press “Done” to complete the setting.
Step 2: Check the connection between the thermostat and its base
Somebody could accidentally have bumped against the thermostat, and now it is not fitting correctly onto the base. A thermostat that is not fitted correctly might cause the display screen to turn blank. If you’ve just installed the thermostat, you also might have fitted it incorrectly.
Press the thermostat securely into position again. If it has been out of position, you’ll hear a click sound when it is correctly fitted again.
If the screen stays blank, you’ll have to troubleshoot further.
Step 3: Check for power issues
As you now know that your Honeywell thermostat is definitely not working and is securely clipped onto its base, your next step is to determine whether the thermostat is receiving power. If it is not receiving power, the screen will be blank.
Check whether the thermostat is switched on
Somebody could have accidentally turned off the thermostat’s switch. Check whether it is switched on. If not, switch it on, and if your Honeywell thermostat’s screen is not blank anymore, you’ve solved the problem.
Check the circuit breaker and ensure it is turned on
Usually, there is only one circuit breaker for the whole HVAC system, including the thermostat, but sometimes the thermostat is connected to its own circuit breaker. If the thermostat servicing the thermostat has tripped, your Honeywell thermostat display screen will stay blank.
The circuit breaker might have tripped because of a power surge. Check the circuit breaker and if tripped, turn it on again. Remember, to turn on a circuit breaker, you have to press the switch completely down and then up until you hear it clicks into position. If the thermostat’s screen lights up, you’ve found the problem.
However, if the circuit breaker trips immediately again, there is an electrical fault somewhere in the system. If you are not a qualified electrician, you’ll have to call your HVAC technician or electrician for help.
Replace the Honeywell thermostat’s batteries
Completely drained or faulty batteries can also cause the thermostat’s screen to turn blank.
So, if the circuit breaker stays on but the thermostat screen stays blank, you’ll next step should be to replace the batteries. Old batteries might be the cause of the blank screen, especially if you haven’t replaced them during the last 12 months. Your Honeywell thermostat is using either 2 AA or 2 AAA alkaline batteries. Your Honeywell manual will tell you whether you have to use AA or AAA batteries, but the easiest is to just replace the older batteries with batteries of the same size. Remember you have to replace both batteries with fresh batteries.
To access the Honeywell thermostat’s batteries, you have to pull out the thermostat’s battery slot at the side of the device. Remove all the old batteries in the slot. Clean the slot from dust and insert the new batteries. Ensure that you place the positive and negative sides of the batteries in the appropriate positions and slide the slot back into the thermostat.
If the thermostat display is still blank, you have to keep on troubleshooting.
Step 4. Check the wiring
If some of the wirings have become loose, the bad connections might cause the thermostat screen to turn blank. If you’ve, just installed your thermostat and the screen doesn’t respond, chances are great that the wires are not connected properly or connected to the wrong terminals.
Before checking the wiring on your thermostat, you have to put off any current flow to your HVAC system, including the thermostat. The easiest is to turn off the relevant circuit breaker(s).
When the power is off, remove the thermostat from its base. The wiring will now be revealed. Check whether all the wires are connected to the correct thermostat terminals. The wiring diagram will be in your user manual or you can view an online video on how to connect your model’s wires. If the wiring is correctly connected, ensure that they all are connected securely and then return the thermostat to its base.
Turn the circuit breaker(s) on again. (I’ve described the correct way to turn on a circuit breaker in Step 3.) If your Honeywell thermostat screen is still blank, continue with the troubleshooting process.
Step 5: Check whether your furnace is on
Usually, Honeywell thermostats generate most of their power from a low-voltage transformer on the HVAC furnace. If the furnace is turned off or not working, it might cause your thermostat’s screen to go blank.
If your furnace is switched off, ensure that the furnace door is closed and switch on the furnace. Usually, you’ll find the furnace switch on a wall beside the furnace. If the furnace doesn’t turn on, check its circuit breaker and turn it on if it has tripped. (Look at the guidelines in Step 3 above to turn the tripped circuit on correctly.) Your furnace should now be on, and the thermostat’s screen should be active. If not, keep on troubleshooting.
Step 6: Check whether Honeywell’s two main safety features are keeping the thermostat screen blank
Honeywell thermostats have built-in features which are designed to protect your HVAC system from damage. These features can stop the system from operating, and when the system is stopped, the thermostat’s screen will, in most instances, turn blank.
To locate the specific location of the safety devices in your HVAC system and thermostat, you might have to call your HVAC technician for advice.
Safety feature 1: Blown Fuse
Some thermostat models are equipped with a built-in fuse. If your thermostat experienced an electrical surge and the circuit breaker is not tripping, the thermostat will blow this built-in fuse and the display screen will turn blank. If you’ve located and replaced the fuse your thermostat will work again and the screen will not be blank anymore.
Safety feature 2: Tripped High Limit Switch
This built-in safety feature protects your HVAC system from overheating. When high temperatures are detected within the system, the high limit switch will trip and thus turn off the thermostat. If the thermostat is off, the display screen will go blank. Locate the high-limit switch and turn it on again.
If this switch is frequently tripping, you’ll have to call your HVAC technician to find the HVAC problem causing the tripping of the switch and fix it.
Step 7: Reset Your Honeywell Thermostat
When you’ve failed to solve the blank screen problem with any of the previous steps, you can reset your Honeywell thermostat. It is easy to reset your Honeywell Thermostat:
- Turn off your Honeywell Thermostat switch.
- Open the battery slot. Usually, you have to press the battery slot’s door down and then slide out the slot.
- When you have access to the batteries, slide them out.
- Then re-insert the batteries but in a reversed position. In other words, the negative terminal should be up, and the positive terminal on the device.
- After about 5 seconds, remove the batteries again and re-insert them in their correct orientation.
- Shut the battery slot by sliding it back into the thermostat.
- After a few seconds, your thermostat’s screen should become active. If not, you have to go to what I call the “Final Step” – call your HVAC technician or get a new thermostat.
Final Step: Call your HVAC technician or get a new thermostat
If your Honeywell thermostat screen still stays blank after you’ve tried all the troubleshooting steps recommended in this article, you have two choices:
- If your thermostat is older than about 10 years, your thermostat may have just reached the end of its lifetime and you will have to replace it with a new Honeywell thermostat.
- If the thermostat is relatively new, call your HVAC technician out to check the whole HVAC system for possible “hidden” problems. After an inspection, the technician will be able to advise you whether the issue can be resolved or whether it would be better to replace the thermostat with another Honeywell thermostat.
Conclusion
Although a blank display screen on your Honeywell thermostat can be very frustrating, it is relatively easy to pinpoint the problem and fix it. And in most instances, homeowners can troubleshoot and fix the issue causing the blank screen themselves.
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