How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the leading thermostat manufacturers, and we proudly install them on a frequent basis in Miami. They’re long-lasting and reliable. Also, Honeywell is frequently improving its technology, offering more features for your household.

Nevertheless, every thermostat can have errors now and again. As a result, we’ve prepared this useful manual to walk you through troubleshooting.

While you can typically fix most thermostat troubles alone, they occasionally require Expert support. Our home comfort pros are ready to assist you when you need us. We’re just a call away at 305-440-1505.

Let’s get started with the process by figuring out what type of thermostat your house 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 experience error codes with this one, but it’s also the least efficient for lowering energy costs.
  • Programmable—This thermostat includes a digital screen and arrows you press to choose your desired temperature. You can also use daily programs to decrease 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, since it adjusts to your schedule. It intuitively raises and lowers the temperature when you or loved ones are gone to help you save on utility bills. You can also change the temperature anywhere on your phone or other Wi-Fi-enabled device. 

As is the case with most technologically advanced things, there are several glitches that might take place. Most of these situations don’t call for pro assistance and are simple to solve by yourself.

Common Honeywell Thermostat Issues

Each thermostat has an exclusive kind of codes that correspond to the troubles that take place.

Think how easy it can be to repair a computer by restarting it. In most cases, diagnosing a thermostat can be just as easy.

Here is a listing the most reported Honeywell thermostat errors. These are applicable to the following programmable thermostats:

Display is Blank

If the display is blank on your programmable thermostat, you might need to get new batteries. If that doesn’t fix the problem or you use a smart thermostat, there might be a wiring issue.

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

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

A loose panel may trigger the safety switch, which disconnects power to the equipment.

Less frequently, a blank display can indicate you should buy a new thermostat.

Comfort Unit Won’t Start

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

During warm weather, confirm you put the thermostat below the current temperature. When it’s cold, verify it’s higher. This sounds silly, but we’ve seen it happen lots of times.

Ensure the power switch near your indoor unit is in the “on” position. You should also comfirm the cabinet doors or panels are secure on your furnace cabinet or air handler. An unsecured panel can trip the safety switch, stopping electricity to the system.

Unit still won’t run? Confirm circuit breakers haven’t flipped and that your HVAC system isn’t experiencing error codes.

“Cool On” or “Heat On” is Blinking

First, check your thermostat is switched to “cool” or “heat.”

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

If these words or the picture is blinking, your thermostat is in a five-minute delay status. This setting keeps your equipment from bad short cycling. This could occur 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 at 305-440-1505 for help.
  • 168—Wi-Fi radio error. Contact 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 restored. No action needed.
  • 181/182—Install a new air filter. Clear the thermostat by tapping “dismiss” after installing a clean filter.
  • 184—Replace humidifier pad. Clear the monitor by hitting “dismiss” after installing a fresh pad filter.
  • 185—Put in a new dehumidifier filter. Clear the thermostat by tapping “dismiss” after installing a clean filter.
  • 187—Wash or replace ventilator filter. Clear the screen by tapping “dismiss” after installing a fresh filter.
  • 188/189—Replace UV bulb. Ring Service Experts Heating & Air Conditioning at 305-440-1505 for support.
  • 210—Register online for exterior temperature. Get the Lyric app to do this step and ensure accurate thermostat operation.
  • 388—Register online for remote access and outside temperature. Use the Lyric app to complete 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 set. Get the Lyric app and follow the procedure to configure your thermostat.

For more specifics, 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 at 305-440-1505 for assistance.
  • 168—Wi-Fi radio error. Contact Service Experts Heating & Air Conditioning at 305-440-1505 for help.
  • 170—Internal memory error. Reach Service Experts Heating & Air Conditioning at 305-440-1505 for help.
  • 171—Set date and time. Complete these settings so scheduling can run.
  • 173—Thermostat temperature sensor error. Contact Service Experts Heating & Air Conditioning at 305-440-1505 for assistance.
  • 175—AC power reconnected. No action necessary.
  • 177—Indoor temperature sensor error. Contact Service Experts Heating & Air Conditioning at 305-440-1505 for help.
  • 178—Outdoor temperature sensor error. Call Service Experts Heating & Air Conditioning at 305-440-1505 for assistance.
  • 181/182—Get a new air filter. Clear the display by hitting “dismiss” after putting in a clean filter.
  • 183—Clean humidifier tank and replace water filter. Clear the thermostat by tapping “dismiss” after completing these procedures.
  • 184—Install a new humidifier pad. Clear the screen by hitting “dismiss” after installing pad filter.
  • 185—Replace dehumidifier filter. Clear the display by tapping “dismiss” after putting in a fresh filter.
  • 186—Rinse ventilator core. Clear the monitor by hitting “dismiss” after completing this task.
  • 187—Rinse or install a new ventilator filter. Clear the display by tapping “dismiss” after installing a new filter.
  • 188/189—Replace UV bulb. Contact Service Experts Heating & Air Conditioning at 305-440-1505 for support.
  • 210—Register online for outside temperature. Get the Lyric app to do this step and ensure proper thermostat operation.
  • 388—Register online for remote access and outside temperature. Get 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. Get the Lyric app and follow the procedures to connect your thermostat.

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

Our Experts are Available to Provide Support

If you’re still experiencing issues after trying the troubleshooting steps, our Experts are ready to support you. Reach us at 305-440-1505 and we’ll arrive as fast as we can to diagnose the issue.

If you rely on a dated thermostat, today is a fantastic time to think about a replacement. Thermostat technology has gotten better in recent years Ask us for more information on how smart thermostats can make your home better while helping save on heating and cooling bills throughout the year.

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