Why is My Honeywell Thermostat Not Working [Troubleshooting]

If your Honeywell thermostat isn’t working, you’re in the right place. Whether you have one of those manual thermostats or a digital thermostat, this guide will answer all the questions. Most of the time, you can troubleshoot the problem yourself without needing professional help.

Common issues with Honeywell thermostats, or really any brand’s thermostat, include screen problems or heating/cooling issues.

Here are some common Honeywell thermostat problems and their respective solutions.

Honeywell Thermostat Display Not Working

This is a problem that occurs with digital thermostats. The unit has no display whatsoever. There could be a number of possibilities behind this.

The easy diagnosis of this blank screen issue is that the batteries have died. If there are no batteries providing power, the Honeywell thermostat will not work or even display anything on the screen. So first, make sure that the batteries are working, and if not, replace them.

Another possible reason is that one of your HVACs access doors is still open. Most modern HVAC systems have this functionality that they don’t turn on until the access doors are shut. Double-check to make sure the doors are closed.

If both of the above are not the causes behind the no display screen, check if the circuit breaker has been tripped. Your HVAC system would likely have its own dedicated breaker, located with other breakers for the home. If it has tripped, simply turn it back on, and the display screen should activate.

Read Also: How to Relocate a Thermostat

Honeywell Thermostat Not Cooling

If you feel like your home’s cooling system is not working and perhaps it’s because of the Honeywell thermostat, there are a few ways to find the problem.

First of all, make sure that the thermostat is set to a cool temperature and is in cool mode. If it’s in auto mode, change it to cool mode and set a lower temperature. Now, wait a while to see if your home feels cool (you can also check the temperature of the air coming out of the vents).

Check if the thermostat has a flashing icon. That indicates that the thermostat is in delay and will turn on in a bit.

If the problem still persists, it’s possible that the problem is with your air conditioner or the thermostat wiring. It could be that the compressor is out of gas.

You can check to ensure if the compressor is the issue before getting into thermostat wires. The compressor is typically located outside the house, and you can hear it running. If it’s running fine, proceed to check the thermostat wiring.

Remove the thermostat from the clasp or unscrew it if it’s attached to the wall by screws. Don’t remove any wires just yet. First, check if all the wires are connected.

Now, check the terminals and see if you have the following terminal configurations:

RC, Y, G

RC (to R), Y, G

RC/R, Y, G, O/B

If it has any of the above configurations, the wiring is fine. If it’s not, consult the manual to fix the configuration.

Honeywell Thermostat Won’t Turn On Heat

If you feel like the heat isn’t turning on timely and that the thermostat isn’t reaching the temperature level, you could check for the following:

  • HVAC access door/furnace door is open
  • Tripped circuit breaker
  • Fan not working

Make sure HVAC access doors, as well as the furnace door, are shut. Also, check if the circuit has tripped. Stand near the vent and see if any air is coming out, which means the fans are working.

You may want to ensure that the furnace is turned on as it has a switch for turning on/off as well.

If none of the above problems exist, it could be that your Honeywell thermostat has wiring issues. Remove to see whether all the wires are indeed attached with their respective terminals. If not, you can consult the owner’s manual to ensure the wiring is done correctly.

You should also check if the thermostat is set on heating mode. It may be a sun or flame icon, or Heat On.

Honeywell Thermostat Not Working After Battery Change

You have to replace batteries from time to time, as Honeywell thermostats don’t normally have rechargeable batteries. However, sometimes the thermostat may not work properly after putting in new batteries.

One possible reason for this could be that you haven’t put the batteries correctly. Putting batteries in the wrong direction is like having no batteries inside. Check the signs where the batteries go and align the terminals correctly.

Batteries in programmable thermostats are aligning in the same direction. It may be different for a non-programmable thermostat.

Another plausible reason is that the new batteries are bad or simply not powerful enough, although that’s rarely the case. You should use AA or AAA batteries as that’s what Honeywell thermostats normally use.

Finally, if the above issues are not really the cause, you should reset the thermostat. That resets it back to the factory settings. This function may or may not be available in your exact model.

Honeywell Thermostat Buttons Don’t Work

For those Honeywell thermostat models that don’t have a touchscreen, buttons are used as controls. Sometimes, the buttons can also stop working.

Commonly, the button pad may be locked. Some thermostats have this feature to prevent children from messing with the buttons. You can unlock the keypad following the instructions on the manual.

Sometimes the inside of the thermostat can get very dirty, preventing buttons from pressing and making contact with the underlying switches. You may need to thoroughly clean the inside of the thermostat.

For that, yank out the thermostat from its housing on the wall. Open it by unscrewing the screws and use a wire brush to clean out all the dust.

If the button still doesn’t work, you may need to replace the button or the whole thermostat. Now, if this occurred during the warranty period (if any), you may contact Honeywell and ask for a replacement device.

Honeywell Wifi Thermostat Connection Problems

The newer thermostats by Honeywell have Wifi connectivity. Wifi connection issues are the most common complaint of users using smart thermostats. Here are some solutions:

  • If the Wifi is not connecting, try turning the Wifi on your phone off and on again.
  • You can also try restarting the Wifi router, as that usually does the trick.
  • If your device is connected to Wifi, but the app is not functioning properly, make sure you’re on the same network as the thermostat.
  • Make sure the router hasn’t reached its max devices number (you can check that in router settings).
  • Some thermostats don’t work on the 5 GHz network (T9/T10 thermostats).
  • Make sure you’re not using mobile data on your phone.
  • Close and reopen the app if it’s not working properly.
  • If the thermostat is online, but the app keeps showing it offline, contact Honeywell support as there might be a hardware issue.


Honeywell thermostat problems can be frustrating, especially when it’s a blistering hot or freezing cold day. Common issues include display problems, heating/cooling issues, or Wifi connectivity trouble.

If the Honeywell thermostat screen is not responding, you should reset the device or check if the batteries are working and inserted correctly. In most cases, you don’t need any help from a professional. Just make sure to go through all the solutions outlined above one by one.

With a lifelong fascination with HVAC mechanics and a mechanical engineering degree from Berkeley, Thomas Johnson boasts years of industry expertise. He founded AirComfortLab.com to fill the void of understandable and useful online information about complex HVAC systems. As the chief editor, Thomas strives to provide accurate and engaging content to help readers make informed HVAC decisions.

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