How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the best thermostat manufacturers, and we proudly install them on a regular basis in the U.S.. They’re sturdy and dependable. Also, Honeywell is regularly advancing its technology, bringing more features for your residence.

Still, all thermostats can experience problems every now and then. That’s why we’ve put together this informative manual to walk you through troubleshooting. While Honeywell thermostat troubleshooting problems are rare, they do pop up.

While you can typically repair many thermostat troubles by yourself, they occasionally call for Expert help. Our home comfort Experts are ready to support you when you need us. We’re only a call away at 866-397-3787.

Let’s start the process by figuring out what type of thermostat your house has.

What Type of Thermostat Do I Have?

There are three models of thermostats:

    • Manual—This is the typical dial-shaped thermostat. You won’t experience error codes with this type, but it’s also the least efficient for reducing utility costs.
    • Programmable—This thermostat has a digital screen and arrows you touch to determine your desired temperature. You can also set daily programs to reduce the temperature when you’re gone and set it higher when you return.
    • Smart—You won’t have to set any programs on this thermostat, as it picks up on your schedule. It automatically adjusts the temperature when you or family members are out and about to help you save on energy bills. You can also change the temperature anywhere using your phone or other Wi-Fi-enabled device.

As is the case with many technologically advanced things, there are several problems that can happen. Many of these problems don’t require pro help and are easy to fix by yourself.

Common Honeywell Thermostat Troubleshooting Errors

Every Honeywell thermostat has a unique kind of codes assigned to the glitches that happen.

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

Here is a listing the most reported Honeywell thermostat errors. These are applicable to the following programmable thermostats:

Display is Blank

If the monitor is empty on your programmable thermostat, you might need to get new batteries. If that doesn’t solve the problem or you rely on a smart thermostat, there could be a wiring malfunction.

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 sturdily secured.

An unsecured panel may trigger the safety switch, which disconnects power to the unit.

While it’s less common, an empty monitor may indicate you need to install a new thermostat.

HVAC Equipment Won’t Run

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

In the summer, confirm you set the thermostat beneath the room temperature. When it’s cold, verify it’s higher. This sounds silly, but we’ve seen it occur lots of times.

Make sure the power switch close to your indoor system is in the “on” position. You should also comfirm the cabinet doors or panels are tight on your furnace cabinet or air handler. An open panel can trip the safety switch, diverting electricity to the equipment.

System still won’t turn on? Verify circuit breakers haven’t turned off and that your HVAC system isn’t experiencing error codes.

“Cool On” or “Heat On” is Flickering

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

Then, check it’s signaling the right unit to start. This is usually demonstrated by “cool on,” “heat on” or an icon.

If these words or the icon is flashing, your thermostat is in a five-minute delay status. This feature keeps your equipment from harmful short cycling. This could happen if you lose power.

Honeywell Thermostat-Specific Error Codes

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

    • 164—Heat pump must be serviced. Call Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for support.
    • 168—Wi-Fi radio error. Contact 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 run.
    • 173—Thermostat temperature sensor error. Contact Lyric technical support at 800-633-3991.
    • 175—AC power resumed. No action necessary.
    • 181/182—Put in a new air filter. Clear the screen by touching “dismiss” after adding a new filter.
    • 184—Put in a new humidifier pad. Clear the screen by hitting “dismiss” after installing a new pad filter.
    • 185—Replace dehumidifier filter. Clear the thermostat by touching “dismiss” after adding a new filter.
    • 187—Clean or put in a new ventilator filter. Clear the screen by touching “dismiss” after installing a clean filter.
    • 188/189—Replace UV bulb. Contact Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for support.
    • 210—Register online for outside temperature. Get the Lyric app to complete this step and ensure proper 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 pick new Wi-Fi network.
    • 508—Wi-Fi not set. Download the Lyric app and follow the process to configure your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005)

    • 164—Heat pump requires service. Reach Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for support.
    • 168—Wi-Fi radio error. Contact Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for assistance.
    • 170—Internal memory error. Contact Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for assistance.
    • 171—Set date and time. Finish these settings so scheduling can work.
    • 173—Thermostat temperature sensor error. Reach Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for assistance.
    • 175—AC power resumed. No action required.
    • 177—Indoor temperature sensor error. Reach Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for help.
    • 178—Outdoor temperature sensor error. Reach Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for assistance.
    • 181/182—Install a new air filter. Clear the display by tapping “dismiss” after putting in a clean filter.
    • 183—Clean humidifier tank and replace water filter. Clear the screen by touching “dismiss” after completing these procedures.
    • 184—Get a new humidifier pad. Clear the display by tapping “dismiss” after installing pad filter.
    • 185—Get a new dehumidifier filter. Clear the display by tapping “dismiss” after putting in a clean filter.
    • 186—Rinse ventilator core. Clear the display by touching “dismiss” after doing this task.
    • 187—Rinse or replace ventilator filter. Clear the display by touching “dismiss” after buying a new filter.
    • 188/189—Replace UV bulb. Get in touch with Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for support.
    • 210—Register online for outdoor temperature. Use the Lyric app to complete this step and ensure accurate thermostat operation.
    • 388—Register online for remote access and outdoor temperature. Download 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 pick new Wi-Fi network.
    • 508—Wi-Fi not set up. Use the Lyric app and follow the steps to connect your thermostat.

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

Our Experts are Ready to Provide Support

If you’re still experiencing problems after going through the troubleshooting steps, our professionals are here to support you. Call us at 866-397-3787 and we’ll be out rapidly to determine the problem.

If you use an aging thermostat, right now is a fantastic time to think over a new device. Thermostat technology has advanced lately Ask us for more details on how smart thermostats can make your house more convenient while helping save on heating and cooling costs year-round.

Savings For You

See All Offers Here >
parts and labor icon

5% off Active Military & Veteran's Discount

  • Get 5% off the price off any equipment install
  • We value our military community and are proud to offer discounts to eligible military personnel

© 2023 Service Experts, Service Experts Heating & Air Conditioning, and the Service Experts logo and design are registered trademarks of Service Experts LLC and used under license by SE Canada Inc. All Rights Reserved. *Not applicable to the Advantage Program. See your signed Advantage Program Agreement for full details and exclusions. 100% Satisfaction Guarantee is subject to certain restrictions and limitations as set forth in the applicable Terms and Conditions.