How to Troubleshoot Honeywell Thermostat Errors

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

Nevertheless, all thermostats can experience problems every so often. As a result, we’ve prepared this useful handbook to walk you through troubleshooting.

While you can typically solve the majority of thermostat issues by yourself, they occasionally need Expert support. 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 finding out what model of thermostat your house has.

What Type of Thermostat Do I Have?

There are three types of thermostats:

  • Manual—This is the typical dial-shaped thermostat. You won’t experience error codes with this one, but it’s also the least efficient for reducing utility expenses.
  • Programmable—This thermostat includes a digital screen and arrows you press to determine your desired temperature. You can also choose daily programs to reduce the temperature when you’re at work and increase it when you come home.
  • Smart—You won’t have to make any programs on this thermostat, since it adjusts to your schedule. It instinctively raises and lowers the temperature when you or other household members are away to help you save on utility expenses. You can also adjust the temperature anywhere using 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 Expert support and are easy to fix by yourself.

Common Honeywell Thermostat Troubles

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

Think how uncomplicated it can be to restore a computer by restarting it. In many instances, correcting a thermostat can be just as uncomplicated.

Here is a listing the most encountered Honeywell thermostat problems. These apply to the following programmable thermostats:

Display is Blank

If the monitor is empty 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 could be a wiring issue.

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 “up”.

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

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

While it’s less common, an empty display could indicate you need to install a new thermostat.

Comfort Equipment Won’t Turn On

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

During warm weather, confirm you put the thermostat lower than the room temperature. In the winter, confirm it’s higher. This sounds absurd, but we’ve seen it happen lots of times.

Make sure the power switch by your indoor equipment 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 trigger the safety switch, stopping current to the unit.

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

“Cool On” or “Heat On” is Blinking

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

Then, verify it’s signaling the right system to start. This is typically 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 status. This feature 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 support.
  • 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. 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—Install a new air filter. Clear the screen by touching “dismiss” after putting in a clean filter.
  • 184—Install a new humidifier pad. Clear the thermostat by tapping “dismiss” after installing a fresh pad filter.
  • 185—Install a new dehumidifier filter. Clear the display by touching “dismiss” after adding a new filter.
  • 187—Rinse or replace ventilator filter. Clear the monitor by tapping “dismiss” after putting in a fresh filter.
  • 188/189—Replace UV bulb. Call Service Experts Heating & Air Conditioning at 866-397-3787 for assistance.
  • 210—Register online for outside temperature. Get 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 link 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 support.
  • 168—Wi-Fi radio error. Call Service Experts Heating & Air Conditioning at 866-397-3787 for support.
  • 170—Internal memory error. Contact 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. Contact Service Experts Heating & Air Conditioning at 866-397-3787 for assistance.
  • 175—AC power resumed. No action needed.
  • 177—Indoor temperature sensor error. Contact Service Experts Heating & Air Conditioning at 866-397-3787 for support.
  • 178—Outdoor temperature sensor error. Contact Service Experts Heating & Air Conditioning at 866-397-3787 for help.
  • 181/182—Install a new air filter. Clear the monitor by tapping “dismiss” after adding a new filter.
  • 183—Rinse humidifier tank and add a new water filter. Clear the display by hitting “dismiss” after doing these steps.
  • 184—Install a new humidifier pad. Clear the monitor by hitting “dismiss” after getting a new pad filter.
  • 185—Replace dehumidifier filter. Clear the screen by tapping “dismiss” after putting in a fresh filter.
  • 186—Clean ventilator core. Clear the display by tapping “dismiss” after finishing this task.
  • 187—Rinse or install a new ventilator filter. Clear the display 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. Use the Lyric app to complete this step and ensure accurate thermostat operation.
  • 388—Register online for remote access and outdoor temperature. Download the Lyric app to finish this step and ensure accurate 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 connected. Download the Lyric app and follow the process to connect your thermostat.

For more information, see 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 an aging thermostat, now is a fantastic time to think over a replacement. Thermostat technology has gotten better in recent years Ask us for more information on how smart thermostats can make your home more convenient while helping save on utility costs year-round.

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