How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the best thermostat manufacturers, and we proudly install them on a frequent basis in the U.S.. They’re long-lasting and trustworthy. Also, Honeywell is frequently updating its technology, offering more features for your household.

Still, all thermostats can run into issues from time to time. Due to this, we’ve put together this informative guidebook to run through troubleshooting. While Honeywell thermostat troubleshooting problems are rare, they happen.

While you can usually repair many thermostat problems on your own, they occasionally require Expert help. Our heating and cooling Experts are ready to assist you when you need us. We’re merely a call away at 866-397-3787.

Let’s begin the process by determining what kind of thermostat your home has.

What Kind of Thermostat Do I Have?

There are three models of thermostats:

  • Manual—This is the older dial-shaped thermostat. You won’t have error codes with this type, but it’s also the least efficient for saving on heating and cooling bills.
  • Programmable—This thermostat features a digital screen and arrows you use to set your desired temperature. You can also use daily programs to lower the temperature when you’re away and raise it when you come home.
  • Smart—You won’t have to schedule any programs on this thermostat, because it adjusts to your day. It automatically raises and lowers the temperature when you or loved ones are away to help you save on heating and cooling bills. You can also change the temperature anywhere using your phone or other Wi-Fi-enabled device.

As is the case with many technologically advanced things, there are several malfunctions that can occur. Most of these problems don’t call for Expert assistance and are uncomplicated enough to fix on your own.

Common Honeywell Thermostat Troubleshooting Errors

All Honeywell thermostats have a special kind of codes assigned to the troubles that occur.

Think how uncomplicated it can be to repair a computer by restarting it. For the most part, diagnosing a thermostat can be just as simple.

Here is a guide to the most common Honeywell thermostat errors. These apply to the following programmable thermostats:

Display is Blank

If the display is empty on your programmable thermostat, you might need to install new batteries. If that doesn’t solve the trouble or you use a smart thermostat, there might be a wiring malfunction.

Next, you should make sure the power is enabled for your furnace or air handler. Verify the switch close to the indoor system is switched “on”.

Also, you should make sure all furnace cabinet or air handler doors/panels are tightly fastened.

A loose panel may trigger the safety switch, which stops power to the unit.

While it’s less common, an empty display might indicate you need to replace your thermostat.

Heating and Cooling Equipment Won’t Turn On

Ensure that your thermostat is set to “cool” or “heat,” not “off.”

In the summer, make sure you schedule the thermostat beneath the room temperature. When it’s cold, verify it’s higher. This sounds silly, but we’ve seen it happen many times.

Confirm the power switch near your indoor system is in the “on” position. You should also make sure the cabinet doors or panels are tight on your furnace cabinet or air handler. A loose panel can trip the safety switch, cutting off power to the system.

Equipment still won’t start? Confirm circuit breakers haven’t turned off and that your HVAC system isn’t showing error codes.

“Cool On” or “Heat On” is Flashing

To start, confirm your thermostat is switched to “cool” or “heat.”

Then, ensure it’s calling for the appropriate equipment to turn on. This is typically demonstrated by “cool on,” “heat on” or an icon.

If this phrase or the picture is pulsing, your thermostat is in a five-minute delay state. This feature stops your unit from bad short cycling. This could take place if your power is interrupted.

Honeywell Thermostat-Specific Error Codes

Honeywell Lyric™ T5 Wi-Fi (RCHT8612WF/RCHT9510WFW)

  • 164—Heat pump needs service. Call Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for assistance.
  • 168—Wi-Fi radio error. Contact Lyric technical support at 800-633-3991. 170—Internal memory error. Call Lyric technical support at 800-633-3991.
  • 171—Set date and time. Finish these settings so scheduling can take place.
  • 173—Thermostat temperature sensor error. Call Lyric technical support at 800-633-3991.
  • 175—AC power resumed. No action required.
  • 181/182—Replace air filter. Clear the monitor by touching “dismiss” after putting in a clean filter.
  • 184—Put in a new humidifier pad. Clear the monitor by hitting “dismiss” after putting in a new pad filter.
  • 185—Replace dehumidifier filter. Clear the thermostat by touching “dismiss” after adding a new filter.
  • 187—Wash or put in a new ventilator filter. Clear the screen by touching “dismiss” after installing a clean filter.
  • 188/189—Replace UV bulb. Ring Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for assistance.
  • 210—Register online for outside temperature. Download the Lyric app to complete this step and ensure accurate thermostat operation.
  • 388—Register online for remote access and outside temperature. Get the Lyric app to do this step and ensure accurate thermostat operation.
  • 399—No Internet. Check your network settings.
  • 400—No Wi-Fi signal. Wait for the thermostat to reconnect or pick new Wi-Fi network.
  • 508—Wi-Fi not configured. Use the Lyric app and follow the procedure to configure your thermostat.

For more details, check this thermostat’s user manual.

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005)

  • 164—Heat pump must be serviced service. Call Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for assistance.
  • 168—Wi-Fi radio error. Contact Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for assistance.
  • 170—Internal memory error. Call Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for assistance.
  • 171—Set date and time. Finish these settings so scheduling can run.
  • 173—Thermostat temperature sensor error. Reach Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for support.
  • 175—AC power reconnected. No action needed.
  • 177—Indoor temperature sensor error. Reach Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for assistance.
  • 178—Outdoor temperature sensor error. Call Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for help.
  • 181/182—Get a new air filter. Clear the monitor by hitting “dismiss” after adding a clean filter.
  • 183—Rinse humidifier tank and add a new water filter. Clear the monitor by hitting “dismiss” after completing these procedures.
  • 184—Install a new humidifier pad. Clear the display by hitting “dismiss” after installing pad filter.
  • 185—Replace dehumidifier filter. Clear the screen by tapping “dismiss” after adding a fresh filter.
  • 186—Rinse ventilator core. Clear the screen by touching “dismiss” after completing this task.
  • 187—Rinse or install a new ventilator filter. Clear the monitor by touching “dismiss” after installing a new filter.
  • 188/189—Get a new UV bulb. Reach Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for help.
  • 210—Register online for outdoor temperature. Get the Lyric app to do this step and ensure correct thermostat operation.
  • 388—Register online for remote access and outdoor temperature. Download the Lyric app to finish this step and ensure proper thermostat operation.
  • 399—No Internet. Verify your network settings.
  • 400—No Wi-Fi signal. Wait for the thermostat to reconnect or select new Wi-Fi network.
  • 508—Wi-Fi not connected. Use the Lyric app and follow the process to connect your thermostat.

For more specifics, look at this thermostat’s user manual.

Our Experts are Ready to Provide Support

If you’re still experiencing problems after working through the troubleshooting process, our pros are available to help. Give us a call at 866-397-3787 and we’ll come to your house as fast as we can to figure out the malfunction.

If you have a dated thermostat, now is a fantastic time to consider a new device. Thermostat technology has come a long way over the last few years. Ask us for more info on how smart thermostats can make your residence more comfortable while helping save on energy costs all year.