How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the best thermostat brands, and we proudly install them on a usual basis in the U.S.. They’re long-lasting and dependable. Also, Honeywell is constantly improving its technology, bringing more features for your house.

However, each thermostat can experience issues now and then. As a result, we’ve prepared this valuable guide to walk you through troubleshooting. While Honeywell thermostat troubleshooting problems are rare, they happen.

While you can often repair the majority of thermostat issues alone, they sometimes need Expert support. Our HVAC professionals are ready to support you when you need us. We’re merely a call away at 866-397-3787.

Let’s begin the process by determining what type of thermostat your house has.

What Kind of Thermostat Do I Have?

There are three models 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 heating and cooling costs.
    • Programmable—This thermostat has a digital screen and arrows you use to set your desired temperature. You can also use daily programs to reduce the temperature when you’re gone and set it higher when you return.
    • Smart—You won’t have to make any programs on this thermostat, as it adjusts to your routine. It intuitively raises and lowers the temperature when you or other household members are gone to help you save on heating and cooling bills. You can also raise or lower the temperature anywhere via your phone or other Wi-Fi-enabled device.

As you know most technologically advanced products, there are several glitches that might occur. Most of these situations don’t call for professional assistance and are simple to fix on your own.

Common Honeywell Thermostat Troubleshooting Problems

All Honeywell thermostats have a unique kind of codes matching the glitches that occur.

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

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

Display is Blank

If the display is clear on your programmable thermostat, you may need to replace the batteries. If that doesn’t fix the trouble or you use a smart thermostat, there may be a wiring issue.

Next, you should ensure the power is flowing for your furnace or air handler. Confirm the switch near the indoor equipment is switched “on”.

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

An unsecured panel may trigger the safety switch, which cuts off power to the system.

Less frequently, an empty monitor could indicate you should get a new thermostat.

HVAC System Won’t Work

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

When it’s hot, confirm you schedule the thermostat lower than the room temperature. When it’s cool, make sure it’s higher. This sounds silly, but we’ve seen it take place many times.

Confirm the power switch by your indoor system is in the “on” position. You should also check the cabinet doors or panels are tight on your furnace cabinet or air handler. An open panel can trip the safety switch, cutting off current to the unit.

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

“Cool On” or “Heat On” is Flickering

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

Then, verify it’s calling for the correct unit to turn on. This is typically indicated 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 setting protects your system from damaging short cycling. This could happen if you lose power.

Honeywell Thermostat-Specific Error Codes

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

    • 164—Heat pump requires service. Call Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for support.
    • 168—Wi-Fi radio error. Call Lyric technical support at 800-633-3991. 170—Internal memory error. Contact Lyric technical support at 800-633-3991.
    • 171—Set date and time. Complete these settings so scheduling can take place.
    • 173—Thermostat temperature sensor error. Contact Lyric technical support at 800-633-3991.
    • 175—AC power resumed. No action required.
    • 181/182—Install a new air filter. Clear the monitor by tapping “dismiss” after putting in a clean filter.
    • 184—Install a new humidifier pad. Clear the monitor by touching “dismiss” after installing a clean pad filter.
    • 185—Install a new dehumidifier filter. Clear the screen by tapping “dismiss” after putting in a fresh filter.
    • 187—Rinse or replace ventilator filter. Clear the screen by touching “dismiss” after installing a fresh filter.
    • 188/189—Get a new UV bulb. Contact Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for help.
    • 210—Register online for outdoor temperature. Use the Lyric app to do this step and ensure proper thermostat operation.
    • 388—Register online for remote access and outdoor temperature. Use the Lyric app to complete 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 configured. Download the Lyric app and follow the steps to configure your thermostat.

For more information, view 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 support.
    • 171—Set date and time. Finalize these settings so scheduling can operate.
    • 173—Thermostat temperature sensor error. Contact Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for support.
    • 175—AC power reconnected. No action required.
    • 177—Indoor temperature sensor error. Call 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 support.
    • 181/182—Get a new air filter. Clear the monitor by touching “dismiss” after installing a fresh filter.
    • 183—Rinse humidifier tank and replace water filter. Clear the screen by tapping “dismiss” after doing these steps.
    • 184—Install a new humidifier pad. Clear the screen by tapping “dismiss” after getting a new pad filter.
    • 185—Get a new dehumidifier filter. Clear the monitor by touching “dismiss” after putting in a clean filter.
    • 186—Wash ventilator core. Clear the thermostat by hitting “dismiss” after completing this task.
    • 187—Wash or get a new ventilator filter. Clear the display by touching “dismiss” after installing a new filter.
    • 188/189—Get a new UV bulb. Get in touch with Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for assistance.
    • 210—Register online for outside temperature. Download the Lyric app to do this step and ensure correct thermostat operation.
    • 388—Register online for remote access and outdoor temperature. Download the Lyric app to finish this step and ensure accurate thermostat operation.
    • 399—No Internet. Verify your network settings.
    • 400—No Wi-Fi signal. Wait for the thermostat to reconnect or select new Wi-Fi network.
    • 508—Wi-Fi not connected. Download the Lyric app and follow the procedures to connect your thermostat.

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

Our Experts are Ready to Provide Assistance

If you’re still experiencing problems after working through the troubleshooting steps, our pros are available to help. Call us at 866-397-3787 and we’ll come to your house as fast as we can to determine the malfunction.

If you use an older thermostat, now is a good time to consider a new thermostat. Thermostat technology has advanced in recent years Ask us for more details on how smart thermostats can make your home better while helping save on utility costs all year.

Savings For You

See All Offers Here >

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.