How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the leading thermostat producers, and we proudly install them on a usual basis in Medina. They’re durable and trustworthy. In addition, Honeywell is constantly enhancing its technology, offering more features for your household.

Nevertheless, each thermostat can have issues every so often. As a result, we’ve compiled this informative handbook to walk you through troubleshooting. While Honeywell thermostat problems are rare, they do pop up. 

While you can typically solve many thermostat issues alone, they sometimes call for Expert support. Our HVAC professionals are here to help when you need us. We’re only a call away at 330-305-2799.

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

What Model of Thermostat Do I Have?

There are three models of thermostats:

  • Manual—This is the classic dial-shaped thermostat. You won’t run into error codes with this one, but it’s also the least efficient for lowering utility expenses.
  • Programmable—This thermostat features a digital screen and arrows you press to determine your desired temperature. You can also choose daily programs to decrease the temperature when you’re gone and set it higher when you get back.
  • Smart—You won’t have to set any programs on this thermostat, as it adjusts to your routine. It intuitively changes the temperature when you or family members are away to help you save on utility expenses. You can also change the temperature anywhere via your phone or other Wi-Fi-enabled device. 

As is the case with the majority of technologically advanced things, there are several problems that may happen. Most of these problems don’t call for Expert assistance and are easy to fix by yourself.

Common Honeywell Thermostat Issues

All thermostats have an exclusive kind of codes that correspond to the glitches that occur.

Think how simple it can be to restore a computer by restarting it. In most situations, diagnosing a thermostat can be just as simple.

Here is a guide to the most common Honeywell thermostat problems. These are applicable to the following programmable thermostats:

Display is Blank

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

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

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

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

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

Heating and Cooling Equipment Won’t Turn On

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

When it’s hot, verify you put the thermostat beneath the ambient temperature. In the winter, confirm it’s higher. This sounds goofy, but we’ve seen it happen a lot 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 tight on your furnace cabinet or air handler. An open panel can trip the safety switch, cutting off power to the system.

Heating or cooling still won’t start? Make sure circuit breakers haven’t turned off and that your HVAC unit isn’t showing error codes.

“Cool On” or “Heat On” is Blinking

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

Then, make sure it’s calling for the appropriate equipment to turn on. This is typically demonstrated by “cool on,” “heat on” or an illustration.

If these words or the illustration is blinking, your thermostat is in a five-minute delay state. This mode stops your equipment from damaging short cycling. This could happen if you lose power.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump needs service. Call Service Experts Heating & Air Conditioning at 330-305-2799 for support.
  • 168—Wi-Fi radio error. Call 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 occur.
  • 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 putting in a new filter.
  • 184—Replace humidifier pad. Clear the screen by hitting “dismiss” after putting in a new pad filter.
  • 185—Install a new dehumidifier filter. Clear the display by tapping “dismiss” after installing a new filter.
  • 187—Wash or replace ventilator filter. Clear the display by tapping “dismiss” after installing a clean filter.
  • 188/189—Get a new UV bulb. Contact Service Experts Heating & Air Conditioning at 330-305-2799 for support.
  • 210—Register online for exterior temperature. Download the Lyric app to do this step and ensure proper thermostat operation.
  • 388—Register online for remote access and outside temperature. Download the Lyric app to finish 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 select new Wi-Fi network.
  • 508—Wi-Fi not configured. Use the Lyric app and follow the procedure to configure your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump requires service. Call Service Experts Heating & Air Conditioning at 330-305-2799 for help.
  • 168—Wi-Fi radio error. Reach Service Experts Heating & Air Conditioning at 330-305-2799 for support.
  • 170—Internal memory error. Reach Service Experts Heating & Air Conditioning at 330-305-2799 for help.
  • 171—Set date and time. Finish these settings so scheduling can run.
  • 173—Thermostat temperature sensor error. Contact Service Experts Heating & Air Conditioning at 330-305-2799 for assistance.
  • 175—AC power restored. No action needed.
  • 177—Indoor temperature sensor error. Call Service Experts Heating & Air Conditioning at 330-305-2799 for support.
  • 178—Outdoor temperature sensor error. Contact Service Experts Heating & Air Conditioning at 330-305-2799 for assistance.
  • 181/182—Get a new air filter. Clear the monitor by hitting “dismiss” after adding a new filter.
  • 183—Rinse humidifier tank and replace water filter. Clear the display by hitting “dismiss” after finishing these tasks.
  • 184—Get a new humidifier pad. Clear the display by touching “dismiss” after installing pad filter.
  • 185—Get a new dehumidifier filter. Clear the screen by tapping “dismiss” after adding a new filter.
  • 186—Rinse ventilator core. Clear the thermostat by hitting “dismiss” after finishing this task.
  • 187—Clean or get a new ventilator filter. Clear the display by hitting “dismiss” after installing a new filter.
  • 188/189—Install a new UV bulb. Reach Service Experts Heating & Air Conditioning at 330-305-2799 for help.
  • 210—Register online for exterior temperature. Use the Lyric app to finish this step and ensure proper thermostat operation.
  • 388—Register online for remote access and outdoor temperature. Get the Lyric app to do this step and ensure correct thermostat operation.
  • 399—No Internet. Check your network settings.
  • 400—No Wi-Fi signal. Wait for the thermostat to reconnect or choose new Wi-Fi network.
  • 508—Wi-Fi not configured. Download the Lyric app and follow the process to connect your thermostat.

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

Our Experts are Here to Provide Support

If you’re still having troubles after going through the troubleshooting process, our professionals are available to help. Give us a call at 330-305-2799 and we’ll come to your house as fast as we can to determine the issue.

If you rely on an older thermostat, now is a great time to think over a replacement. Thermostat technology has come a long way lately Ask us for more details on how smart thermostats can make your home comfier while helping save on utility costs all year.

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