How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the leading thermostat producers, and we proudly install them on a frequent basis in Dayton. They’re durable and dependable. Also, Honeywell is frequently updating its technology, offering more features for your home.

Still, all thermostats can have troubles now and again. That’s why we’ve put together this helpful manual to run through troubleshooting. While Honeywell thermostat problems are rare, they happen. 

While you can often repair most thermostat troubles on your own, they occasionally require Expert support. Our home comfort pros are here to support you when you need us. We’re only a call away at 937-503-7896.

Let’s begin the process by finding out what type of thermostat your residence has.

What Kind of Thermostat Do I Have?

There are three kinds of thermostats:

  • Manual—This is the typical dial-shaped thermostat. You won’t run into error codes with this kind, but it’s also the least efficient for reducing heating and cooling costs.
  • Programmable—This thermostat includes a digital screen and arrows you touch to determine your desired temperature. You can also use daily programs to decrease the temperature when you’re gone and increase it when you return.
  • Smart—You won’t have to schedule any programs on this thermostat, since it picks up on your schedule. It instinctively changes the temperature when you or loved ones are away to help you save on energy bills. You can also raise or lower the temperature anywhere on your phone or other Wi-Fi-enabled device. 

As you’re aware the majority of technologically advanced things, there are several problems that can occur. Many of these troubles don’t call for professional assistance and are uncomplicated enough to solve on your own.

Common Honeywell Thermostat Problems

Each thermostat has a unique group of codes assigned to the troubles that happen.

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

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

Display is Blank

If the display is empty on your programmable thermostat, you may need to replace the batteries. If that doesn’t take care of the trouble or you rely on a smart thermostat, there may be a wiring issue.

Next, you should check the power is enabled for your furnace or air handler. Verify the switch near the indoor system is switched “up”.

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

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

Less frequently, a blank display can indicate you will need to get a new thermostat.

Heating and Cooling Equipment Won’t Run

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

In the summer, confirm you set the thermostat below the ambient temperature. In the winter, make sure it’s higher. This sounds absurd, but we’ve seen it happen lots of times.

Make sure the power switch by your indoor unit is in the “on” position. You should also make sure the cabinet doors or panels are closed on your furnace cabinet or air handler. An open panel can activate the safety switch, cutting off electricity to the unit.

Unit still won’t turn on? Confirm circuit breakers haven’t flipped and that your HVAC unit isn’t experiencing error codes.

“Cool On” or “Heat On” is Flickering

To begin, confirm your thermostat is switched to “cool” or “heat.”

Then, verify it’s telling the correct equipment to run. This is usually indicated by “cool on,” “heat on” or an icon.

If these words or the icon is flashing, your thermostat is in a five-minute delay mode. This mode stops your unit from damaging short cycling. This may happen if your power is interrupted.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump needs service. Call Stevenson Service Experts at 937-503-7896 for support.
  • 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. Complete these settings so scheduling can run.
  • 173—Thermostat temperature sensor error. Reach Lyric technical support at 800-633-3991.
  • 175—AC power restored. No action required.
  • 181/182—Replace air filter. Clear the thermostat by touching “dismiss” after installing a clean filter.
  • 184—Put in a new humidifier pad. Clear the thermostat by tapping “dismiss” after adding a fresh pad filter.
  • 185—Replace dehumidifier filter. Clear the screen by hitting “dismiss” after installing a new filter.
  • 187—Clean or install a new ventilator filter. Clear the monitor by touching “dismiss” after adding a clean filter.
  • 188/189—Get a new UV bulb. Ring Stevenson Service Experts at 937-503-7896 for help.
  • 210—Register online for outdoor temperature. Get the Lyric app to finish this step and ensure accurate thermostat operation.
  • 388—Register online for remote access and exterior temperature. Get 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. Use the Lyric app and follow the process to link your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump requires service. Reach Stevenson Service Experts at 937-503-7896 for assistance.
  • 168—Wi-Fi radio error. Contact Stevenson Service Experts at 937-503-7896 for help.
  • 170—Internal memory error. Contact Stevenson Service Experts at 937-503-7896 for assistance.
  • 171—Set date and time. Finalize these settings so scheduling can operate.
  • 173—Thermostat temperature sensor error. Call Stevenson Service Experts at 937-503-7896 for assistance.
  • 175—AC power restored. No action necessary.
  • 177—Indoor temperature sensor error. Contact Stevenson Service Experts at 937-503-7896 for assistance.
  • 178—Outdoor temperature sensor error. Call Stevenson Service Experts at 937-503-7896 for assistance.
  • 181/182—Get a new air filter. Clear the display by hitting “dismiss” after installing a clean filter.
  • 183—Wash humidifier tank and add a new water filter. Clear the display by touching “dismiss” after completing these tasks.
  • 184—Install a new humidifier pad. Clear the monitor by hitting “dismiss” after adding a new pad filter.
  • 185—Get a new dehumidifier filter. Clear the thermostat by hitting “dismiss” after adding a fresh filter.
  • 186—Wash ventilator core. Clear the thermostat by touching “dismiss” after finishing this task.
  • 187—Clean or install a new ventilator filter. Clear the monitor by hitting “dismiss” after installing a new filter.
  • 188/189—Add a new UV bulb. Contact Stevenson Service Experts at 937-503-7896 for support.
  • 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 outside temperature. Use the Lyric app to finish this step and ensure correct 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 configured. Download the Lyric app and follow the procedures to connect your thermostat.

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

Our Experts are Ready to Help

If you’re still running into issues after trying the troubleshooting steps, our Experts are available to support you. Reach us at 937-503-7896 and we’ll arrive quickly to determine the malfunction.

If you use a dated thermostat, today is a great time to think over a new thermostat. Thermostat technology has gotten better in recent years Ask us for more info on how smart thermostats can make your home comfier while helping save on utility costs year-round.

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