How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the top thermostat brands, and we proudly install them on a frequent basis in Cleveland. They’re long-lasting and dependable. In addition, Honeywell is constantly enhancing its technology, resulting in more features for your household.

Still, every thermostat can experience problems at times. As a result, we’ve compiled this valuable manual to run through troubleshooting. While Honeywell thermostat problems are rare, they do pop up. 

While you can usually fix the majority of thermostat troubles by yourself, they sometimes require Expert help. Our heating and cooling professionals are ready to assist you when you need us. We’re merely a call away at 440-252-1375.

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

What Type of Thermostat Do I Have?

There are three kinds of thermostats:

  • Manual—This is the classic dial-shaped thermostat. You won’t run into error codes with this one, but it’s also the least efficient for reducing energy expenses.
  • Programmable—This thermostat has a digital screen and arrows you use to choose your desired temperature. You can also use daily programs to reduce the temperature when you’re gone and set it higher when you return.
  • Smart—You won’t have to schedule any programs on this thermostat, as it adjusts to your schedule. It automatically adjusts the temperature when you or family members are out and about to help you save on utility costs. You can also change the temperature anywhere via your phone or other Wi-Fi-enabled device. 

As is the case with most technologically advanced solutions, there are several glitches that might occur. The majority of of these troubles don’t require Expert help and are easy to repair alone.

Common Honeywell Thermostat Problems

All thermostats have an exclusive group of codes that correspond to the glitches that occur.

Think how easy it can be to fix a computer by restarting it. For the most part, troubleshooting a thermostat can be just as easy.

Here is a guide to the most reported Honeywell thermostat issues. These involve the following programmable thermostats:

Display is Blank

If the monitor is clear on your programmable thermostat, you might need to get new batteries. If that doesn’t take care of the problem or you use a smart thermostat, there may be a wiring issue.

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

Also, you should confirm all furnace cabinet or air handler doors/panels are tightly in place.

A panel that isn’t tight may activate the safety switch, which disconnects power to the equipment.

While it’s less common, an empty monitor can indicate you need to get a new thermostat.

HVAC Equipment Won’t Run

Check that your thermostat is on “cool” or “heat,” not “off.”

In the summer, make sure you schedule the thermostat below the ambient temperature. When it’s cool, verify it’s higher. This sounds absurd, but we’ve seen it take place many times.

Ensure the power switch by your indoor equipment is in the “on” position. You should also make sure the cabinet doors or panels are secure on your furnace cabinet or air handler. A loose panel can trip the safety switch, diverting power to the unit.

Heating or cooling still won’t run? Make sure circuit breakers haven’t turned off and that your HVAC unit isn’t experiencing error codes.

“Cool On” or “Heat On” is Flickering

To begin, check your thermostat is set to “cool” or “heat.”

Then, ensure it’s calling for the right unit to run. This is typically indicated by “cool on,” “heat on” or an illustration.

If this set of words or the picture is flashing, your thermostat is in a five-minute delay state. This mode stops your unit from bad short cycling. This can occur if your power is interrupted.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump must be serviced. Call Service Experts Heating & Air Conditioning at 440-252-1375 for assistance.
  • 168—Wi-Fi radio error. Reach Lyric technical support at 800-633-3991. 170—Internal memory error. Reach Lyric technical support at 800-633-3991.
  • 171—Set date and time. Finalize these settings so scheduling can occur.
  • 173—Thermostat temperature sensor error. Call Lyric technical support at 800-633-3991.
  • 175—AC power restored. No action necessary.
  • 181/182—Put in a new air filter. Clear the thermostat by tapping “dismiss” after installing a fresh filter.
  • 184—Put in a new humidifier pad. Clear the thermostat by tapping “dismiss” after installing a clean pad filter.
  • 185—Put in a new dehumidifier filter. Clear the thermostat by hitting “dismiss” after adding a fresh filter.
  • 187—Clean or install a new ventilator filter. Clear the screen by touching “dismiss” after installing a fresh filter.
  • 188/189—Install a new UV bulb. Contact Service Experts Heating & Air Conditioning at 440-252-1375 for support.
  • 210—Register online for outside temperature. Use the Lyric app to complete this step and ensure correct thermostat operation.
  • 388—Register online for remote access and exterior temperature. Use the Lyric app to do this step and ensure accurate 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 set. Use the Lyric app and follow the steps to connect your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump must be serviced service. Reach Service Experts Heating & Air Conditioning at 440-252-1375 for assistance.
  • 168—Wi-Fi radio error. Call Service Experts Heating & Air Conditioning at 440-252-1375 for assistance.
  • 170—Internal memory error. Contact Service Experts Heating & Air Conditioning at 440-252-1375 for help.
  • 171—Set date and time. Finalize these settings so scheduling can work.
  • 173—Thermostat temperature sensor error. Contact Service Experts Heating & Air Conditioning at 440-252-1375 for help.
  • 175—AC power restored. No action needed.
  • 177—Indoor temperature sensor error. Contact Service Experts Heating & Air Conditioning at 440-252-1375 for support.
  • 178—Outdoor temperature sensor error. Contact Service Experts Heating & Air Conditioning at 440-252-1375 for help.
  • 181/182—Get a new air filter. Clear the screen by tapping “dismiss” after putting in a fresh filter.
  • 183—Rinse humidifier tank and add a new water filter. Clear the monitor by hitting “dismiss” after completing these steps.
  • 184—Install a new humidifier pad. Clear the monitor by tapping “dismiss” after adding a new pad filter.
  • 185—Get a new dehumidifier filter. Clear the thermostat by tapping “dismiss” after putting in a fresh filter.
  • 186—Rinse ventilator core. Clear the thermostat by touching “dismiss” after completing this task.
  • 187—Rinse or get a new ventilator filter. Clear the display by tapping “dismiss” after installing a new filter.
  • 188/189—Add a new UV bulb. Reach Service Experts Heating & Air Conditioning at 440-252-1375 for assistance.
  • 210—Register online for outdoor temperature. Download the Lyric app to complete this step and ensure proper thermostat operation.
  • 388—Register online for remote access and outdoor temperature. Use the Lyric app to complete this step and ensure correct thermostat operation.
  • 399—No Internet. Confirm your network settings.
  • 400—No Wi-Fi signal. Wait for the thermostat to reconnect or pick new Wi-Fi network.
  • 508—Wi-Fi not set up. Use the Lyric app and follow the process to connect your thermostat.

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

Our Experts are Available to Provide Support

If you’re still having issues after working through the troubleshooting steps, our professionals are ready to assist you. Give us a call at 440-252-1375 and we’ll be out as fast as we can to figure out the issue.

If you have an older thermostat, today is a fantastic time to think about a replacement. Thermostat technology has advanced over the last few years. Ask us for more details on how smart thermostats can make your residence more convenient while helping save on heating and cooling expenses all year.

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