How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the leading thermostat brands, and we proudly install them on a regular basis in Canada. They’re long-lasting and dependable. In addition, Honeywell is constantly improving its technology, bringing more features for your house.

Nevertheless, all thermostats can run into problems every so often. Due to this, we’ve prepared this useful handbook to walk you through troubleshooting.

While you can often repair many thermostat issues by yourself, they often call for Expert help. Our heating and cooling pros are ready to help when you need us. We’re only a call away at 866-397-3787.

Let’s start the process by determining what model of thermostat your residence has.

What Model of Thermostat Do I Have?

There are three types of thermostats:

  • Manual—This is the older dial-shaped thermostat. You won’t have error codes with this one, but it’s also the least efficient for reducing energy expenses.
  • Programmable—This thermostat includes a digital screen and arrows you press to choose your desired temperature. You can also choose daily programs to reduce the temperature when you’re at work and set it higher when you come home.
  • Smart—You won’t have to schedule any programs on this thermostat, as it picks up on your schedule. It instinctively changes the temperature when you or other household members are away to help you save on utility expenses. You can also adjust the temperature anywhere on your phone or other Wi-Fi-enabled device. 

As is the case with most technologically advanced products, there are common problems that may occur. Many of these troubles don’t call for pro help and are easy to fix alone.

Common Honeywell Thermostat Troubles

Each thermostat has a unique group of codes matching the problems that occur.

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

Here is a listing the most reported Honeywell thermostat problems. These include the following programmable thermostats:

Display is Blank

If the screen is clear on your programmable thermostat, you might need to put in new batteries. If that doesn’t take care of the malfunction or you rely on a smart thermostat, there may be a wiring problem.

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

In addition to that, you should confirm all furnace cabinet or air handler doors/panels are sturdily in place.

An unsecured panel may trigger the safety switch, which stops power to the equipment.

While it’s less common, a clear display could signify you need to install a new thermostat.

Heating and Cooling Unit Won’t Turn On

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

During warm weather, confirm you put the thermostat lower than the ambient temperature. In the winter, verify it’s higher. This sounds goofy, but we’ve seen it happen a lot of times.

Make sure the power switch close to your indoor system is in the “on” position. You should also make sure the cabinet doors or panels are closed on your furnace cabinet or air handler. A loose panel can trigger the safety switch, stopping electricity to the unit.

Heating or cooling still won’t run? Confirm circuit breakers haven’t tripped and that your HVAC unit isn’t showing error codes.

“Cool On” or “Heat On” is Blinking

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

Then, make sure it’s signaling the correct system to turn on. This is often shown by “cool on,” “heat on” or an icon.

If these words or the icon is flashing, your thermostat is in a five-minute delay state. This setting keeps your system from damaging short cycling. This may happen if you lose power.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump requires service. Call Service Experts Heating & Air Conditioning at 866-397-3787 for help.
  • 168—Wi-Fi radio error. Contact 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 occur.
  • 173—Thermostat temperature sensor error. Call Lyric technical support at 800-633-3991.
  • 175—AC power resumed. No action required.
  • 181/182—Put in a new air filter. Clear the screen by touching “dismiss” after adding a clean filter.
  • 184—Install 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 display by touching “dismiss” after putting in a new filter.
  • 187—Wash or replace ventilator filter. Clear the screen by hitting “dismiss” after adding a clean filter.
  • 188/189—Replace UV bulb. Call Service Experts Heating & Air Conditioning at 866-397-3787 for assistance.
  • 210—Register online for exterior temperature. Use the Lyric app to complete this step and ensure proper thermostat operation.
  • 388—Register online for remote access and outside temperature. Download the Lyric app to do 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 pick new Wi-Fi network.
  • 508—Wi-Fi not configured. Use the Lyric app and follow the process to configure your thermostat.

For more information, check 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 866-397-3787 for help.
  • 168—Wi-Fi radio error. Call Service Experts Heating & Air Conditioning at 866-397-3787 for support.
  • 170—Internal memory error. Reach Service Experts Heating & Air Conditioning at 866-397-3787 for assistance.
  • 171—Set date and time. Finish these settings so scheduling can operate.
  • 173—Thermostat temperature sensor error. Reach Service Experts Heating & Air Conditioning at 866-397-3787 for assistance.
  • 175—AC power resumed. No action necessary.
  • 177—Indoor temperature sensor error. Reach Service Experts Heating & Air Conditioning at 866-397-3787 for help.
  • 178—Outdoor temperature sensor error. Reach Service Experts Heating & Air Conditioning at 866-397-3787 for help.
  • 181/182—Get a new air filter. Clear the screen by tapping “dismiss” after adding a new filter.
  • 183—Wash humidifier tank and install a new water filter. Clear the display by hitting “dismiss” after doing these procedures.
  • 184—Get a new humidifier pad. Clear the monitor by hitting “dismiss” after getting a new pad filter.
  • 185—Replace dehumidifier filter. Clear the thermostat by hitting “dismiss” after adding a clean filter.
  • 186—Clean ventilator core. Clear the display by hitting “dismiss” after finishing this task.
  • 187—Rinse or install a new ventilator filter. Clear the monitor by touching “dismiss” after getting a new filter.
  • 188/189—Get a new UV bulb. Get in touch with Service Experts Heating & Air Conditioning at 866-397-3787 for help.
  • 210—Register online for outside temperature. Get the Lyric app to complete 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 correct thermostat operation.
  • 399—No Internet. Confirm your network settings.
  • 400—No Wi-Fi signal. Wait for the thermostat to reconnect or choose new Wi-Fi network.
  • 508—Wi-Fi not set up. Download the Lyric app and follow the procedures to connect your thermostat.

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

Our Experts are Available to Provide Assistance

If you’re still experiencing problems after trying the troubleshooting process, our Experts are here to assist you. Reach us at 866-397-3787 and we’ll be out quickly to diagnose the malfunction.

If you rely on a dated thermostat, now is a fantastic time to think over a replacement. Thermostat technology has gotten better lately Ask us for more information on how smart thermostats can make your home more convenient while helping save on utility expenses year-round.

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