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How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the best thermostat brands, and we proudly install them on a frequent basis in Oakville. They’re durable and trustworthy. Plus, Honeywell is constantly improving its technology, resulting in more features for your family.

Nevertheless, all thermostats can run into problems occasionally. Due to this, we’ve put together this useful guide to run through troubleshooting.

While you can typically repair the majority of thermostat troubles by yourself, they sometimes need Expert assistance. Our HVAC pros are ready to support you when you need us. We’re only a call away at 289-813-5566.

Let’s begin the process by figuring out what model of thermostat your home has.

What Model of Thermostat Do I Have?

There are three models of thermostats:

  • Manual—This is the typical dial-shaped thermostat. You won’t have error codes with this one, but it’s also the least efficient for reducing energy bills.
  • Programmable—This thermostat includes a digital screen and arrows you press to determine your desired temperature. You can also use daily programs to reduce the temperature when you’re away and increase it when you come home.
  • Smart—You won’t have to make any programs on this thermostat, since it adjusts to your routine. It intuitively changes the temperature when you or family members are out and about to help you save on heating and cooling costs. You can also change the temperature anywhere using your phone or other Wi-Fi-enabled device. 

As is the case with most technologically advanced things, there are several malfunctions that can happen. Most of these situations don’t need pro help and are simple to repair alone.

Common Honeywell Thermostat Troubles

Each thermostat has a special group of codes matching the troubles that take place.

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

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

Display is Blank

If the display is empty on your programmable thermostat, you may need to put in new batteries. If that doesn’t fix the issue or you have a smart thermostat, there may be a wiring issue.

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

Also, you should make sure all furnace cabinet or air handler doors/panels are securely fastened.

A loose panel may activate the safety switch, which cuts off power to the equipment.

Infrequently, an empty screen may indicate you need to install a new thermostat.

Heating and Cooling Unit Won’t Run

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

In the summer, make sure you put the thermostat beneath the current temperature. When it’s cool, verify it’s higher. This sounds absurd, but we’ve seen it happen a lot of times.

Ensure the power switch near 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. An open panel can trigger the safety switch, stopping power to the equipment.

System still won’t start? Confirm circuit breakers haven’t flipped and that your HVAC equipment isn’t showing error codes.

“Cool On” or “Heat On” is Flickering

First, verify your thermostat is switched to “cool” or “heat.”

Then, verify it’s calling for the correct unit to turn on. This is often demonstrated 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 state. This feature protects your equipment from bad short cycling. This could occur if you lose electricity.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump requires service. Call Abbey Air Service Experts at 289-813-5566 for assistance.
  • 168—Wi-Fi radio error. Reach 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 run.
  • 173—Thermostat temperature sensor error. Contact Lyric technical support at 800-633-3991.
  • 175—AC power restarted. No action required.
  • 181/182—Put in a new air filter. Clear the thermostat by tapping “dismiss” after installing a fresh filter.
  • 184—Put in a new humidifier pad. Clear the thermostat by tapping “dismiss” after installing a fresh pad filter.
  • 185—Replace dehumidifier filter. Clear the display by touching “dismiss” after installing a fresh filter.
  • 187—Clean or install a new ventilator filter. Clear the screen by touching “dismiss” after adding a clean filter.
  • 188/189—Install a new UV bulb. Call Abbey Air Service Experts at 289-813-5566 for support.
  • 210—Register online for outdoor temperature. Get the Lyric app to finish this step and ensure proper thermostat operation.
  • 388—Register online for remote access and outdoor temperature. Use 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 configured. Get the Lyric app and follow the procedure to configure your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump must be serviced service. Contact Abbey Air Service Experts at 289-813-5566 for support.
  • 168—Wi-Fi radio error. Contact Abbey Air Service Experts at 289-813-5566 for support.
  • 170—Internal memory error. Contact Abbey Air Service Experts at 289-813-5566 for support.
  • 171—Set date and time. Complete these settings so scheduling can run.
  • 173—Thermostat temperature sensor error. Reach Abbey Air Service Experts at 289-813-5566 for support.
  • 175—AC power restored. No action required.
  • 177—Indoor temperature sensor error. Reach Abbey Air Service Experts at 289-813-5566 for support.
  • 178—Outdoor temperature sensor error. Contact Abbey Air Service Experts at 289-813-5566 for assistance.
  • 181/182—Install a new air filter. Clear the display by touching “dismiss” after adding a fresh filter.
  • 183—Clean humidifier tank and install a new water filter. Clear the thermostat by touching “dismiss” after doing these tasks.
  • 184—Replace humidifier pad. Clear the thermostat by touching “dismiss” after adding a new pad filter.
  • 185—Install a new dehumidifier filter. Clear the screen by tapping “dismiss” after putting in a new filter.
  • 186—Wash ventilator core. Clear the thermostat by touching “dismiss” after completing this task.
  • 187—Clean or get a new ventilator filter. Clear the display by tapping “dismiss” after installing a new filter.
  • 188/189—Replace UV bulb. Contact Abbey Air Service Experts at 289-813-5566 for help.
  • 210—Register online for outside temperature. Use the Lyric app to finish this step and ensure accurate thermostat operation.
  • 388—Register online for remote access and exterior temperature. Download 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 up. Use the Lyric app and follow the process to connect your thermostat.

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

Our Experts are Here to Provide Support

If you’re still running into problems after going through the troubleshooting steps, our pros are ready to help. Reach us at 289-813-5566 and we’ll arrive rapidly to diagnose the issue.

If you use a dated thermostat, now is a good time to consider a new device. Thermostat technology has advanced over the last few years. Ask us for more information on how smart thermostats can make your house more convenient while helping save on utility bills throughout the year.

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