How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the best thermostat manufacturers, and we proudly install them on a regular basis in Hillsborough. They’re sturdy and dependable. Plus, Honeywell is constantly improving its technology, resulting in more features for your household.

However, every thermostat can have problems every now and then. Due to this, we’ve compiled this helpful manual to go over troubleshooting.

While you can usually repair the majority of thermostat issues by yourself, they often call for Expert help. Our HVAC professionals are available to help when you need us. We’re only a call away at 908-448-2154.

Let’s get started with the process by figuring out what type of thermostat your residence has.

What Model of Thermostat Do I Have?

There are three kinds of thermostats:

  • Manual—This is the older dial-shaped thermostat. You won’t have error codes with this one, but it’s also the least efficient for reducing utility bills.
  • Programmable—This thermostat has a digital screen and arrows you use 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 return.
  • Smart—You won’t have to schedule any programs on this thermostat, because it picks up on your routine. It automatically raises and lowers the temperature when you or family members are gone to help you save on energy expenses. You can also change the temperature anywhere via your phone or other Wi-Fi-enabled device. 

As you know most technologically advanced solutions, there are regular malfunctions that might happen. Most of these situations don’t need professional support and are easy to solve on your own.

Common Honeywell Thermostat Problems

Each thermostat has a special group of codes that correspond to the malfunctions that occur.

Think how easy it can be to repair a computer by restarting it. For the most part, troubleshooting a thermostat can be just as simple.

Here are some of the most reported Honeywell thermostat issues. These are applicable to the following programmable thermostats:

Display is Blank

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

Next, you should check the power is on for your furnace or air handler. Verify the switch by the indoor unit is switched “on”.

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

An unsecured panel may trigger the safety switch, which stops power to the equipment.

While it’s less common, a blank screen can mean you should install a new thermostat.

HVAC System Won’t Run

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

When it’s hot, verify you put the thermostat lower than the current temperature. When it’s cold, make sure it’s higher. This sounds absurd, but we’ve seen it happen many 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. A loose panel can trigger the safety switch, diverting power to the equipment.

System still won’t turn on? Make sure circuit breakers haven’t tripped and that your HVAC system isn’t displaying error codes.

“Cool On” or “Heat On” is Blinking

To begin, verify your thermostat is on “cool” or “heat.”

Then, make sure it’s calling for the right system to turn on. This is typically demonstrated by “cool on,” “heat on” or a picture.

If this set of words or the picture is pulsing, your thermostat is in a five-minute delay status. This feature keeps your system from harmful short cycling. This can take place if your power is interrupted.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump requires service. Call Fras-Air/General Service Experts at 908-448-2154 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. Complete these settings so scheduling can run.
  • 173—Thermostat temperature sensor error. Contact Lyric technical support at 800-633-3991.
  • 175—AC power resumed. No action needed.
  • 181/182—Install a new air filter. Clear the monitor by tapping “dismiss” after installing a new filter.
  • 184—Put in a new humidifier pad. Clear the thermostat by tapping “dismiss” after installing a clean pad filter.
  • 185—Replace dehumidifier filter. Clear the thermostat by touching “dismiss” after adding a clean filter.
  • 187—Clean or put in a new ventilator filter. Clear the thermostat by hitting “dismiss” after putting in a new filter.
  • 188/189—Get a new UV bulb. Contact Fras-Air/General Service Experts at 908-448-2154 for assistance.
  • 210—Register online for outside temperature. Get the Lyric app to finish this step and ensure accurate thermostat operation.
  • 388—Register online for remote access and outside temperature. Use the Lyric app to do 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 select new Wi-Fi network.
  • 508—Wi-Fi not set up. Use the Lyric app and follow the procedure to configure your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump must be serviced service. Call Fras-Air/General Service Experts at 908-448-2154 for support.
  • 168—Wi-Fi radio error. Call Fras-Air/General Service Experts at 908-448-2154 for assistance.
  • 170—Internal memory error. Contact Fras-Air/General Service Experts at 908-448-2154 for support.
  • 171—Set date and time. Complete these settings so scheduling can work.
  • 173—Thermostat temperature sensor error. Call Fras-Air/General Service Experts at 908-448-2154 for support.
  • 175—AC power resumed. No action required.
  • 177—Indoor temperature sensor error. Call Fras-Air/General Service Experts at 908-448-2154 for help.
  • 178—Outdoor temperature sensor error. Reach Fras-Air/General Service Experts at 908-448-2154 for assistance.
  • 181/182—Replace air filter. Clear the thermostat by tapping “dismiss” after putting in a clean filter.
  • 183—Wash humidifier tank and replace water filter. Clear the screen by hitting “dismiss” after doing these procedures.
  • 184—Get a new humidifier pad. Clear the monitor by tapping “dismiss” after getting a new pad filter.
  • 185—Replace dehumidifier filter. Clear the monitor by hitting “dismiss” after adding a new filter.
  • 186—Rinse ventilator core. Clear the screen by tapping “dismiss” after finishing this task.
  • 187—Wash or get a new ventilator filter. Clear the monitor by hitting “dismiss” after getting a new filter.
  • 188/189—Add a new UV bulb. Get in touch with Fras-Air/General Service Experts at 908-448-2154 for assistance.
  • 210—Register online for outside temperature. Download the Lyric app to finish this step and ensure correct thermostat operation.
  • 388—Register online for remote access and exterior temperature. Use 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 pick new Wi-Fi network.
  • 508—Wi-Fi not set up. Download the Lyric app and follow the process to connect your thermostat.

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

Our Experts are Here to Provide Assistance

If you’re still experiencing issues after working through the troubleshooting list, our Experts are ready to assist you. Call us at 908-448-2154 and we’ll arrive rapidly to figure out the malfunction.

If you rely on an aging thermostat, today is a fantastic time to think about a new device. Thermostat technology has gotten better lately Ask us for more information on how smart thermostats can make your house more comfortable while helping save on energy costs throughout the year.

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