How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the best thermostat brands, and we proudly install them on a regular basis in the U.S.. They’re sturdy and trustworthy. In addition, Honeywell is constantly improving its technology, bringing more features for your household.

Still, every thermostat can run into issues occasionally. As a result, we’ve compiled this valuable guidebook to walk you through troubleshooting. While Honeywell thermostat troubleshooting problems are rare, they do pop up.

While you can often solve most thermostat problems by yourself, they often require Expert support. Our home comfort Experts are ready to assist you when you need us. We’re just a call away at 866-397-3787.

Let’s get started with the process by figuring out what kind of thermostat your home has.

What Kind 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 kind, but it’s also the least efficient for saving on utility expenses.
    • Programmable—This thermostat includes a digital screen and arrows you touch to set your desired temperature. You can also set daily programs to decrease the temperature when you’re away and set it higher when you get back.
    • Smart—You won’t have to set any programs on this thermostat, as it picks up on your day. It automatically adjusts the temperature when you or family members are gone to help you save on energy costs. You can also adjust the temperature anywhere via your phone or other Wi-Fi-enabled device.

As you’re aware many technologically advanced things, there are regular malfunctions that may happen. Many of these troubles don’t call for Expert support and are simple to repair on your own.

Common Honeywell Thermostat Troubleshooting Problems

Each Honeywell thermostat has a special set of codes assigned to the malfunctions that occur.

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

Here is a listing 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 might need to install new batteries. If that doesn’t take care of the issue or you use a smart thermostat, there may be a wiring issue.

Next, you should make sure the power is enabled for your furnace or air handler. Make sure the switch by the indoor equipment is switched “up”.

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

A loose panel may trigger the safety switch, which stops power to the equipment.

While it’s less common, a clear display might indicate you need to buy a new thermostat.

Comfort Equipment Won’t Turn On

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

In the summer, make sure you put the thermostat beneath the ambient temperature. In the winter, verify it’s higher. This sounds goofy, but we’ve seen it occur a lot of times.

Make sure the power switch by 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 trigger the safety switch, cutting off electricity to the equipment.

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

“Cool On” or “Heat On” is Flashing

To start, ensure your thermostat is switched to “cool” or “heat.”

Then, ensure it’s signaling the correct unit to turn on. This is typically shown by “cool on,” “heat on” or an icon.

If these words or the illustration is pulsing, your thermostat is in a five-minute delay state. This feature stops your equipment from damaging short cycling. This may take place 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 assistance.
    • 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. Call Lyric technical support at 800-633-3991.
    • 175—AC power restarted. No action needed.
    • 181/182—Install a new air filter. Clear the thermostat by tapping “dismiss” after installing a clean filter.
    • 184—Replace humidifier pad. Clear the display by tapping “dismiss” after putting in a clean pad filter.
    • 185—Install a new dehumidifier filter. Clear the display by tapping “dismiss” after adding a fresh filter.
    • 187—Clean or replace ventilator filter. Clear the thermostat 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. Use the Lyric app to finish this step and ensure correct 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 select new Wi-Fi network.
    • 508—Wi-Fi not set up. Download the Lyric app and follow the procedure to link your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005)

    • 164—Heat pump needs service. Reach Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for help.
    • 168—Wi-Fi radio error. Call 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. Finalize these settings so scheduling can work.
    • 173—Thermostat temperature sensor error. Contact Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for help.
    • 175—AC power reconnected. No action needed.
    • 177—Indoor temperature sensor error. Call Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for support.
    • 178—Outdoor temperature sensor error. Reach Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for help.
    • 181/182—Install a new air filter. Clear the display by tapping “dismiss” after putting in a fresh filter.
    • 183—Clean humidifier tank and replace water filter. Clear the thermostat by tapping “dismiss” after completing these tasks.
    • 184—Install a new humidifier pad. Clear the monitor by hitting “dismiss” after getting a new pad filter.
    • 185—Get a new dehumidifier filter. Clear the monitor by tapping “dismiss” after adding a new filter.
    • 186—Wash ventilator core. Clear the screen by touching “dismiss” after doing this task.
    • 187—Wash or get a new ventilator filter. Clear the monitor by tapping “dismiss” after installing a new filter.
    • 188/189—Replace UV bulb. Reach Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for help.
    • 210—Register online for outside temperature. Get the Lyric app to complete this step and ensure accurate thermostat operation.
    • 388—Register online for remote access and outside temperature. Get the Lyric app to complete 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. Get the Lyric app and follow the steps to connect your thermostat.

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

Our Experts are Ready to Provide Support

If you’re still having issues after going through the troubleshooting steps, our pros are here to help. Call us at 866-397-3787 and we’ll arrive quickly to diagnose the problem.

If you rely on a dated thermostat, today is a good time to consider a replacement. Thermostat technology has gotten better in recent years Ask us for more information on how smart thermostats can make your house more comfortable while helping save on heating and cooling bills all year.

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