How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the best thermostat manufacturers, and we proudly install them on a regular basis in Charlotte. They’re durable and trustworthy. Also, Honeywell is constantly enhancing its technology, bringing more features for your household.

Nevertheless, each thermostat can experience issues now and then. As a result, we’ve compiled this informative manual to walk you through troubleshooting.

While you can typically repair most thermostat troubles alone, they occasionally need Expert support. Our home comfort pros are here to support you when you need us. We’re merely a call away at 704-464-4307.

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

What Model of Thermostat Do I Have?

There are three kinds 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 saving on utility costs.
  • Programmable—This thermostat includes a digital screen and arrows you press to determine your desired temperature. You can also set daily programs to lower the temperature when you’re away and set it higher when you come home.
  • Smart—You won’t have to set any programs on this thermostat, as it picks up on your routine. It automatically adjusts the temperature when you or family members are gone to help you save on energy expenses. You can also adjust the temperature anywhere using your phone or other Wi-Fi-enabled device. 

As you’re aware many technologically advanced products, there are common glitches that can take place. Many of these situations don’t require pro support and are easy to solve alone.

Common Honeywell Thermostat Troubles

Every thermostat has a unique kind of codes assigned to the troubles that occur.

Think how easy it can be to fix a computer by restarting it. Many times, troubleshooting a thermostat can be just as easy.

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

Display is Blank

If the monitor is blank on your programmable thermostat, you may need to install new batteries. If that doesn’t take care of the issue or you rely on a smart thermostat, there could be a wiring malfunction.

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

In addition to that, you should confirm all furnace cabinet or air handler doors/panels are securely secured.

An unsecured panel may activate the safety switch, which disconnects power to the equipment.

Infrequently, a clear monitor can signify you need to get a new thermostat.

Heating and Cooling Unit Won’t Turn On

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

In the summer, confirm you schedule the thermostat below the room temperature. In the winter, verify it’s higher. This sounds absurd, but we’ve seen it happen lots of 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 secure on your furnace cabinet or air handler. A loose panel can trip the safety switch, cutting off current to the system.

Equipment still won’t start? Verify circuit breakers haven’t tripped and that your HVAC unit isn’t displaying error codes.

“Cool On” or “Heat On” is Flashing

First, confirm your thermostat is set to “cool” or “heat.”

Then, ensure it’s telling the right system to run. This is usually demonstrated by “cool on,” “heat on” or an illustration.

If this phrase or the picture is flashing, your thermostat is in a five-minute delay state. This setting keeps your system from bad short cycling. This may happen 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 704-464-4307 for assistance.
  • 168—Wi-Fi radio error. Contact Lyric technical support at 800-633-3991. 170—Internal memory error. Call Lyric technical support at 800-633-3991.
  • 171—Set date and time. Complete 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 needed.
  • 181/182—Put in a new air filter. Clear the display by tapping “dismiss” after installing a new filter.
  • 184—Put in a new humidifier pad. Clear the monitor by tapping “dismiss” after installing a new pad filter.
  • 185—Install a new dehumidifier filter. Clear the monitor by tapping “dismiss” after putting in a new filter.
  • 187—Wash or replace ventilator filter. Clear the monitor by tapping “dismiss” after adding a clean filter.
  • 188/189—Install a new UV bulb. Call Service Experts Heating & Air Conditioning at 704-464-4307 for help.
  • 210—Register online for exterior temperature. Get the Lyric app to do this step and ensure proper thermostat operation.
  • 388—Register online for remote access and exterior temperature. Download the Lyric app to do this step and ensure proper 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 steps to configure your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump needs service. Reach Service Experts Heating & Air Conditioning at 704-464-4307 for support.
  • 168—Wi-Fi radio error. Contact Service Experts Heating & Air Conditioning at 704-464-4307 for assistance.
  • 170—Internal memory error. Reach Service Experts Heating & Air Conditioning at 704-464-4307 for help.
  • 171—Set date and time. Complete these settings so scheduling can operate.
  • 173—Thermostat temperature sensor error. Contact Service Experts Heating & Air Conditioning at 704-464-4307 for assistance.
  • 175—AC power resumed. No action required.
  • 177—Indoor temperature sensor error. Call Service Experts Heating & Air Conditioning at 704-464-4307 for assistance.
  • 178—Outdoor temperature sensor error. Call Service Experts Heating & Air Conditioning at 704-464-4307 for assistance.
  • 181/182—Get a new air filter. Clear the thermostat by touching “dismiss” after adding a fresh filter.
  • 183—Wash humidifier tank and add a new water filter. Clear the monitor by tapping “dismiss” after doing these steps.
  • 184—Replace humidifier pad. Clear the monitor by hitting “dismiss” after getting a new pad filter.
  • 185—Install a new dehumidifier filter. Clear the screen by touching “dismiss” after adding a fresh filter.
  • 186—Wash ventilator core. Clear the screen by tapping “dismiss” after completing this task.
  • 187—Clean or get a new ventilator filter. Clear the monitor by hitting “dismiss” after buying a new filter.
  • 188/189—Replace UV bulb. Get in touch with Service Experts Heating & Air Conditioning at 704-464-4307 for assistance.
  • 210—Register online for exterior temperature. Get the Lyric app to finish this step and ensure accurate thermostat operation.
  • 388—Register online for remote access and exterior temperature. Get the Lyric app to finish this step and ensure correct 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 connected. Get the Lyric app and follow the process to connect your thermostat.

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

Our Experts are Available to Provide Support

If you’re still running into issues after working through the troubleshooting steps, our pros are here to support you. Reach us at 704-464-4307 and we’ll come to your house as fast as we can to diagnose the issue.

If you rely on an older thermostat, now is a fantastic time to think about a new thermostat. Thermostat technology has advanced lately Ask us for more information on how smart thermostats can make your house more convenient while helping save on utility expenses year-round.

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