A blank display on a White Rodgers or Emerson thermostat is almost always a low-power issue. So the most common solution is to replace the batteries.
But if you’ve done that already, don’t worry. In this guide, I’ll walk you through what else you can do to fix a blank or frozen display.
Step 1: Try Controlling the Thermostat Via the App
If you've got a Sensi Smart-style thermostat linked up with the Sensi app, you can try to control the app remotely.
If the app doesn't put out any errors or messages implying that the connection between the thermostat is lost:
- Try adjusting the temperature and changing the system mode via the app.
- If the app shows everything running smoothly, check the vents or HVAC equipment to confirm that the system is operating according to the new instructions provided in the app.
When the app seems to be able to control the thermostat, but the display is blank, the device may have a broken display or have ran into a glitch.
In that case, I recommend controlling the device remotely until you can try out the rest of the steps or get it looked at by a pro.
Step 2: Make Sure the Thermostat is Firmly Pressed In
In certain models without batteries, the display won't work if the connections are loose.
So to make sure the pins on the baseplate, align properly with the thermostat, remove the thermostat from the wall mount and reinstall, making sure it clicks into place and fits tightly into the wall mount.
Then, see if the thermostat restarts and controls the HVAC equipment successfully.
If you weren't able to resolve the issue using the steps mentioned above, you will have to dig deeper, inside the thermostat wires, breakers, and HVAC equipment. Diagnosing electrical wiring is potentially dangerous and can cause electrical shock and damage to equipment.
So I highly recommend following the necessary safety procedures or getting help from a professional if you aren't comfortable doing it yourself.
Step 3: Check the Breakers for the System
Before you start digging around the thermostat wiring or resetting the thermostat, it's important to check if any breakers have been tripped.
So head over to your circuit board and check the breakers assigned to your thermostat and HVAC system. If you find any that have tripped, try restoring them and see if the thermostat powers up.
You can also check the safety disconnects, fuses, and wall outlets, for the HVAC equipment, to make sure they haven't tripped.
However, if you don't know how to handle these switches or the breakers keep flipping back on, there might be an electrical leak or short circuit.
In that case, it's best to get help from a professional.
Step 4: Replace the Batteries on the Thermostat
Since most thermostats won't put out a proper notification, or others will quickly die out without enough time to notify the user, dead batteries can become overlooked; hence, replacing the batteries is always worth a shot.
To replace the batteries, simply remove the thermostat from the wall mount and replace the batteries at the back of the display or on the wall mount itself, making sure the polarities are correct.
Step 5: Restart/Reset the Thermostat
Prior to diagnosing the wiring or checking the HVAC equipment, it's best to perform a soft restart or factory reset of the thermostat.
Depending on the model, there are different ways to carry this out. However, to soft-restart the device, without losing your settings, you can:
- Take out the thermostat from the wall mount.
- If it includes batteries: remove one battery.
- Reinsert the batteries or reinstall the thermostat back into the wall, making sure you do it a few seconds after the display goes blank.
Switching off power to the thermostat quickly ensures the device retains its memory and reboots to clear out any glitches or software errors.
However, this may not always work, so depending on your model, a factory reset might be necessary.
Step 6: Check the Thermostat Wiring Terminals
Taking a good look at the thermostat wires is a good idea. The wires might be loose or you might be missing a C-wire, which is crucial if you want to improve power stability.
- So remove the thermostat from the wall mount and see if all the wiring terminals are properly installed.
- Make sure the wires are installed according to their proper designations and that the wires are not dirty or riddled with dust or corrosion.
- If you don't mind doing a little electrical DIY, you can remove the wires and see if they are properly stripped, and re-strip them if necessary.
- However, make sure to turn off the power to the thermostat before doing so.
- Then, take a photo of the wiring setup and see if the wires match up with the wiring terminals at the other end of the thermostat cable. (Which is, usually, the furnace control board).
- If you find any mismatched wires, make sure to recorrect them so the wires are installed in the correct terminals.
- If you have a multimeter, you can also check the voltage or for any short connections between each of the thermostat wires. However, make sure you follow the necessary safety precautions such as wearing insulated clothing, shoes, etc.. and avoid touching any live wires.
Step 7: Check the HVAC Equipment
Since most HVAC systems provide power to the thermostat, the thermostat may also stop responding or display a blank screen when the entire HVAC system is down.
This is why I recommended taking a look at the breakers or safety switches right from the get-go.
However, if you carried out all the above steps and confirmed that the thermostat wiring is dead. It's worth taking a look inside the furnace and HVAC equipment or getting help from a professional.
Some things to look out for are:
- Clogged filters or drain pipes.
- Faulty control boards.
- Blown fuses inside the control boards.
- Bad capacitors.
- Broken relays or contactors.
- Malfunctioning flame sensors.
- Leaking coolant
The list goes on. So make sure to check these out or get a pro to help.
Final Step: Replace the Thermostat
In a worst-case scenario, the thermostat might be damaged. So if you went through all the above steps and also confirmed that the HVAC equipment is operating smoothly, then it's time to replace or repair the thermostat.
If you have an old thermostat laying around, I recommend installing it and using the HVAC system until you can get a new thermostat.