How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the top thermostat brands, and we proudly install them on a frequent basis in Clearwater. They’re long-lasting and reliable. Also, Honeywell is regularly improving its technology, resulting in more features for your residence.

However, all thermostats can have troubles at times. That’s why we’ve prepared this valuable manual to run through troubleshooting.

While you can typically solve the majority of thermostat problems on your own, they often call for Expert support. Our home comfort pros are ready to help when you need us. We’re only a call away at 727-219-2471.

Let’s begin the process by determining what type of thermostat your house has.

What Type of Thermostat Do I Have?

There are three types of thermostats:

  • Manual—This is the older dial-shaped thermostat. You won’t run into error codes with this one, but it’s also the least efficient for reducing energy bills.
  • Programmable—This thermostat has a digital screen and arrows you touch to determine your desired temperature. You can also choose daily programs to lower the temperature when you’re at work and raise it when you come home.
  • Smart—You won’t have to set any programs on this thermostat, since it learns your schedule. It intuitively changes the temperature when you or loved ones are out and about to help you save on energy bills. You can also raise or lower the temperature anywhere via your phone or other Wi-Fi-enabled device. 

As is the case with the majority of technologically advanced solutions, there are regular problems that might take place. Many of these issues don’t require pro help and are uncomplicated enough to solve alone.

Common Honeywell Thermostat Problems

Each thermostat has a special kind of codes matching the troubles that occur.

Think how easy 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 common Honeywell thermostat errors. These apply to the following programmable thermostats:

Display is Blank

If the screen is empty on your programmable thermostat, you might need to replace the batteries. If that doesn’t solve the issue or you rely on a smart thermostat, there might be a wiring malfunction.

Next, you should check the power is enabled for your furnace or air handler. Confirm the switch by the indoor equipment is switched “up”.

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

An unsecured panel may activate the safety switch, which cuts off power to the unit.

While it’s less common, a clear display can indicate you will need to buy a new thermostat.

Comfort Unit Won’t Start

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

When it’s hot, confirm you schedule the thermostat lower than the current temperature. In the winter, make sure it’s higher. This sounds silly, but we’ve seen it take place a lot of times.

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

Unit still won’t run? Confirm circuit breakers haven’t tripped and that your HVAC unit isn’t displaying error codes.

“Cool On” or “Heat On” is Flickering

To begin, check your thermostat is set to “cool” or “heat.”

Then, verify it’s signaling the right system to start. This is often indicated by “cool on,” “heat on” or an icon.

If this set of words or the illustration is blinking, your thermostat is in a five-minute delay mode. This feature protects your unit from bad short cycling. This could take place if you lose power.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump requires service. Call Midway Services at 727-219-2471 for support.
  • 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. Complete these settings so scheduling can run.
  • 173—Thermostat temperature sensor error. Contact Lyric technical support at 800-633-3991.
  • 175—AC power restored. No action required.
  • 181/182—Install a new air filter. Clear the thermostat by hitting “dismiss” after installing a clean filter.
  • 184—Replace humidifier pad. Clear the display by tapping “dismiss” after installing a clean pad filter.
  • 185—Install a new dehumidifier filter. Clear the monitor by hitting “dismiss” after installing a clean filter.
  • 187—Rinse or install a new ventilator filter. Clear the thermostat by tapping “dismiss” after putting in a fresh filter.
  • 188/189—Replace UV bulb. Contact Midway Services at 727-219-2471 for help.
  • 210—Register online for exterior temperature. Get the Lyric app to complete 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 proper thermostat operation.
  • 399—No Internet. Confirm your network settings.
  • 400—No Wi-Fi signal. Wait for the thermostat to reconnect or select new Wi-Fi network.
  • 508—Wi-Fi not set. Get the Lyric app and follow the steps to configure your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump needs service. Call Midway Services at 727-219-2471 for assistance.
  • 168—Wi-Fi radio error. Reach Midway Services at 727-219-2471 for help.
  • 170—Internal memory error. Call Midway Services at 727-219-2471 for assistance.
  • 171—Set date and time. Complete these settings so scheduling can operate.
  • 173—Thermostat temperature sensor error. Reach Midway Services at 727-219-2471 for assistance.
  • 175—AC power reconnected. No action required.
  • 177—Indoor temperature sensor error. Contact Midway Services at 727-219-2471 for support.
  • 178—Outdoor temperature sensor error. Call Midway Services at 727-219-2471 for support.
  • 181/182—Get a new air filter. Clear the screen by hitting “dismiss” after putting in a clean filter.
  • 183—Wash humidifier tank and install a new water filter. Clear the display by tapping “dismiss” after completing these tasks.
  • 184—Get a new humidifier pad. Clear the display by hitting “dismiss” after getting a new pad filter.
  • 185—Get a new dehumidifier filter. Clear the monitor by tapping “dismiss” after putting in a new filter.
  • 186—Clean ventilator core. Clear the monitor by hitting “dismiss” after finishing this task.
  • 187—Wash or install a new ventilator filter. Clear the monitor by tapping “dismiss” after installing a new filter.
  • 188/189—Get a new UV bulb. Reach Midway Services at 727-219-2471 for help.
  • 210—Register online for outdoor temperature. Use the Lyric app to do this step and ensure correct thermostat operation.
  • 388—Register online for remote access and exterior temperature. Download 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 connected. Get the Lyric app and follow the steps to connect your thermostat.

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

Our Experts are Ready to Help

If you’re still running into troubles after working through the troubleshooting list, our professionals are ready to support you. Reach us at 727-219-2471 and we’ll come to your house quickly to figure out the issue.

If you use a dated thermostat, now is a fantastic time to think over a replacement. Thermostat technology has come a long way over the last few years. Ask us for more info on how smart thermostats can make your home more comfortable while helping save on heating and cooling costs throughout the year.

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