How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the leading thermostat manufacturers, and we proudly install them on a frequent basis in Waldorf. They’re durable and dependable. Plus, Honeywell is regularly enhancing its technology, bringing more features for your residence.

However, all thermostats can experience errors at times. Due to this, we’ve compiled this useful guidebook to walk you through troubleshooting.

While you can typically repair many thermostat problems alone, they occasionally require Expert help. Our home comfort Experts are available to assist you when you need us. We’re just a call away at 301-747-3140.

Let’s start the process by determining what model of thermostat your house has.

What Model of Thermostat Do I Have?

There are three kinds of thermostats:

  • Manual—This is the classic dial-shaped thermostat. You won’t run into error codes with this type, but it’s also the least efficient for saving on energy expenses.
  • Programmable—This thermostat includes a digital screen and arrows you touch to choose your desired temperature. You can also set daily programs to lower the temperature when you’re away and increase it when you get back.
  • Smart—You won’t have to schedule any programs on this thermostat, since it picks up on your day. It intuitively adjusts the temperature when you or loved ones are away to help you save on heating and cooling costs. You can also raise or lower the temperature anywhere using your phone or other Wi-Fi-enabled device. 

As you’re aware the majority of technologically advanced solutions, there are regular problems that can occur. Many of these situations don’t need professional help and are easy to solve on your own.

Common Honeywell Thermostat Problems

Every thermostat has a special kind of codes that correspond to the glitches that happen.

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

Here are some of the most common Honeywell thermostat problems. These involve the following programmable thermostats:

Display is Blank

If the display is clear on your programmable thermostat, you might need to put in new batteries. If that doesn’t take care of the issue or you use a smart thermostat, there might be a wiring issue.

Next, you should check the power is flowing for your furnace or air handler. Verify the switch near the indoor equipment is in the “on” position.

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

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

Infrequently, an empty screen can indicate you should buy a new thermostat.

Heating and Cooling Unit Won’t Run

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

In the summer, confirm you put the thermostat lower than the room temperature. When it’s cool, make sure it’s higher. This sounds goofy, but we’ve seen it occur lots of times.

Ensure the power switch by your indoor equipment 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, stopping electricity to the system.

Equipment still won’t run? Confirm circuit breakers haven’t turned off and that your HVAC equipment isn’t displaying error codes.

“Cool On” or “Heat On” is Flashing

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

Then, make sure it’s calling for the appropriate unit to run. This is often demonstrated by “cool on,” “heat on” or an icon.

If this set of words or the icon is blinking, your thermostat is in a five-minute delay mode. This mode stops your unit from bad short cycling. This may occur if your power is interrupted.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump needs service. Call A-PLUS Service Experts at 301-747-3140 for help.
  • 168—Wi-Fi radio error. Call Lyric technical support at 800-633-3991. 170—Internal memory error. Call Lyric technical support at 800-633-3991.
  • 171—Set date and time. Finish these settings so scheduling can occur.
  • 173—Thermostat temperature sensor error. Reach Lyric technical support at 800-633-3991.
  • 175—AC power restored. No action required.
  • 181/182—Install a new air filter. Clear the display by hitting “dismiss” after installing a new filter.
  • 184—Replace humidifier pad. Clear the monitor by tapping “dismiss” after putting in a fresh pad filter.
  • 185—Replace dehumidifier filter. Clear the monitor by touching “dismiss” after adding a new filter.
  • 187—Rinse or replace ventilator filter. Clear the thermostat by hitting “dismiss” after putting in a clean filter.
  • 188/189—Replace UV bulb. Call A-PLUS Service Experts at 301-747-3140 for assistance.
  • 210—Register online for exterior temperature. Download the Lyric app to do this step and ensure correct thermostat operation.
  • 388—Register online for remote access and outside temperature. Use the Lyric app to complete 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. Download the Lyric app and follow the steps to connect your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump requires service. Contact A-PLUS Service Experts at 301-747-3140 for help.
  • 168—Wi-Fi radio error. Call A-PLUS Service Experts at 301-747-3140 for help.
  • 170—Internal memory error. Reach A-PLUS Service Experts at 301-747-3140 for assistance.
  • 171—Set date and time. Finish these settings so scheduling can operate.
  • 173—Thermostat temperature sensor error. Contact A-PLUS Service Experts at 301-747-3140 for help.
  • 175—AC power reconnected. No action needed.
  • 177—Indoor temperature sensor error. Reach A-PLUS Service Experts at 301-747-3140 for assistance.
  • 178—Outdoor temperature sensor error. Reach A-PLUS Service Experts at 301-747-3140 for support.
  • 181/182—Replace air filter. Clear the monitor by tapping “dismiss” after installing a new filter.
  • 183—Rinse humidifier tank and replace water filter. Clear the screen by touching “dismiss” after completing these procedures.
  • 184—Get a new humidifier pad. Clear the thermostat by touching “dismiss” after getting a new pad filter.
  • 185—Install a new dehumidifier filter. Clear the screen by tapping “dismiss” after adding a clean filter.
  • 186—Rinse ventilator core. Clear the display by touching “dismiss” after completing this task.
  • 187—Wash or replace ventilator filter. Clear the monitor by tapping “dismiss” after buying a new filter.
  • 188/189—Get a new UV bulb. Get in touch with A-PLUS Service Experts at 301-747-3140 for assistance.
  • 210—Register online for outdoor temperature. Get the Lyric app to do this step and ensure accurate thermostat operation.
  • 388—Register online for remote access and outdoor 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 choose new Wi-Fi network.
  • 508—Wi-Fi not set up. Use the Lyric app and follow the process to connect your thermostat.

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

Our Experts are Available to Help

If you’re still running into issues after trying the troubleshooting steps, our pros are available to assist you. Reach us at 301-747-3140 and we’ll come to your house as fast as we can to diagnose the problem.

If you have an aging thermostat, today is a fantastic time to think about a new thermostat. Thermostat technology has advanced over the last few years. Ask us for more information on how smart thermostats can make your residence more convenient while helping save on heating and cooling expenses throughout the year.

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