How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the leading thermostat manufacturers, and we proudly install them on a frequent basis in Cocoa. They’re sturdy and trustworthy. In addition, Honeywell is constantly enhancing its technology, resulting in more features for your house.

However, each thermostat can run into troubles at one time or another. As a result, we’ve put together this helpful handbook to run through troubleshooting.

While you can usually solve most thermostat issues on your own, they occasionally require Expert assistance. Our heating and cooling Experts are available to help when you need us. We’re just a call away at 321-428-7635.

Let’s begin the process by figuring out what model of thermostat your home has.

What Kind 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 lowering utility bills.
  • Programmable—This thermostat includes a digital screen and arrows you touch to choose your desired temperature. You can also choose daily programs to reduce the temperature when you’re gone and increase it when you return.
  • Smart—You won’t have to set any programs on this thermostat, since it learns your day. It instinctively changes the temperature when you or family members are away to help you save on heating and cooling expenses. You can also change the temperature anywhere via your phone or other Wi-Fi-enabled device. 

As is the case with the majority of technologically advanced things, there are regular glitches that might occur. Most of these issues don’t require pro assistance and are simple to solve on your own.

Common Honeywell Thermostat Problems

Each thermostat has a special set of codes that correspond to the troubles that occur.

Think how simple it can be to restore a computer by restarting it. Many times, diagnosing a thermostat can be just as easy.

Here is a guide to the most encountered Honeywell thermostat problems. 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 take care of the malfunction or you rely on a smart thermostat, there might be a wiring issue.

Next, you should ensure the power is enabled for your furnace or air handler. Verify the switch near the indoor unit is in the “on” position.

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

An unsecured panel may trigger the safety switch, which disconnects power to the unit.

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

Heating and Cooling Unit Won’t Work

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

In the summer, confirm you set the thermostat below the ambient temperature. When it’s cold, make sure it’s higher. This sounds goofy, but we’ve seen it take place many times.

Ensure the power switch by your indoor unit is in the “on” position. You should also make sure the cabinet doors or panels are closed on your furnace cabinet or air handler. An open panel can trigger the safety switch, cutting off current to the equipment.

Unit still won’t run? Make sure circuit breakers haven’t tripped and that your HVAC equipment isn’t showing error codes.

“Cool On” or “Heat On” is Flickering

To start, ensure your thermostat is set to “cool” or “heat.”

Then, verify it’s calling for the right system to run. This is often shown by “cool on,” “heat on” or a picture.

If these words or the icon is blinking, your thermostat is in a five-minute delay mode. This feature stops your unit from damaging short cycling. This can take place if you lose power.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump needs service. Call Service Experts Heating & Air Conditioning at 321-428-7635 for help.
  • 168—Wi-Fi radio error. Call Lyric technical support at 800-633-3991. 170—Internal memory error. Contact Lyric technical support at 800-633-3991.
  • 171—Set date and time. Finish these settings so scheduling can run.
  • 173—Thermostat temperature sensor error. Call Lyric technical support at 800-633-3991.
  • 175—AC power resumed. No action necessary.
  • 181/182—Install a new air filter. Clear the thermostat by tapping “dismiss” after putting in a fresh filter.
  • 184—Put in a new humidifier pad. Clear the screen by touching “dismiss” after installing a fresh pad filter.
  • 185—Install a new dehumidifier filter. Clear the monitor by hitting “dismiss” after adding a new filter.
  • 187—Clean or replace ventilator filter. Clear the screen by tapping “dismiss” after adding a clean filter.
  • 188/189—Install a new UV bulb. Contact Service Experts Heating & Air Conditioning at 321-428-7635 for support.
  • 210—Register online for exterior temperature. Get the Lyric app to finish this step and ensure correct thermostat operation.
  • 388—Register online for remote access and exterior temperature. Use the Lyric app to finish 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 configured. Download the Lyric app and follow the process to configure your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump must be serviced service. Contact Service Experts Heating & Air Conditioning at 321-428-7635 for support.
  • 168—Wi-Fi radio error. Contact Service Experts Heating & Air Conditioning at 321-428-7635 for assistance.
  • 170—Internal memory error. Reach Service Experts Heating & Air Conditioning at 321-428-7635 for assistance.
  • 171—Set date and time. Finalize these settings so scheduling can run.
  • 173—Thermostat temperature sensor error. Call Service Experts Heating & Air Conditioning at 321-428-7635 for support.
  • 175—AC power reconnected. No action necessary.
  • 177—Indoor temperature sensor error. Call Service Experts Heating & Air Conditioning at 321-428-7635 for assistance.
  • 178—Outdoor temperature sensor error. Reach Service Experts Heating & Air Conditioning at 321-428-7635 for help.
  • 181/182—Replace air filter. Clear the display by tapping “dismiss” after installing a new filter.
  • 183—Rinse humidifier tank and install a new water filter. Clear the thermostat by touching “dismiss” after completing these tasks.
  • 184—Replace humidifier pad. Clear the monitor by hitting “dismiss” after installing pad filter.
  • 185—Get a new dehumidifier filter. Clear the screen by hitting “dismiss” after installing a fresh filter.
  • 186—Clean ventilator core. Clear the screen by tapping “dismiss” after completing this task.
  • 187—Rinse or replace ventilator filter. Clear the screen by tapping “dismiss” after buying a new filter.
  • 188/189—Get a new UV bulb. Contact Service Experts Heating & Air Conditioning at 321-428-7635 for support.
  • 210—Register online for exterior temperature. Use the Lyric app to finish 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 choose new Wi-Fi network.
  • 508—Wi-Fi not configured. Use the Lyric app and follow the steps to connect your thermostat.

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

Our Experts are Here to Help

If you’re still experiencing issues after trying the troubleshooting list, our pros are here to assist you. Give us a call at 321-428-7635 and we’ll arrive quickly to figure out the problem.

If you rely on an older thermostat, now is a good time to consider a replacement. Thermostat technology has gotten better over the last few years. Ask us for more info on how smart thermostats can make your house more comfortable while helping save on energy costs year-round.

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