How to Troubleshoot Honeywell Thermostat Errors

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

Nevertheless, all thermostats can run into troubles every so often. Due to this, we’ve put together this informative guidebook to walk you through troubleshooting. While Honeywell thermostat troubleshooting problems are rare, they do pop up.

While you can usually fix most thermostat problems alone, they sometimes call for Expert support. Our home comfort Experts are here to assist you when you need us. We’re only a call away at 866-397-3787.

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

What Kind of Thermostat Do I Have?

There are three types of thermostats:

    • Manual—This is the classic dial-shaped thermostat. You won’t run into error codes with this one, but it’s also the least efficient for reducing energy bills.
    • Programmable—This thermostat features a digital screen and arrows you touch to choose your desired temperature. You can also set daily programs to lower the temperature when you’re away and increase it when you return.
    • Smart—You won’t have to schedule any programs on this thermostat, as it picks up on your schedule. It intuitively adjusts the temperature when you or other household members are gone to help you save on energy expenses. You can also adjust the temperature anywhere on your phone or other Wi-Fi-enabled device.

As is the case with many technologically advanced solutions, there are several malfunctions that might take place. Many of these troubles don’t call for professional support and are uncomplicated enough to solve on your own.

Common Honeywell Thermostat Troubleshooting Errors

All Honeywell thermostats have a unique group of codes assigned to the malfunctions that take place.

Think how easy it can be to fix a computer by restarting it. In most situations, diagnosing a thermostat can be just as easy.

Here is a listing the most common Honeywell thermostat problems. These apply to the following programmable thermostats:

Display is Blank

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

Next, you should ensure the power is on for your furnace or air handler. Make sure the switch by the indoor system is switched “on”.

In addition to that, you should make sure all furnace cabinet or air handler doors/panels are securely secured.

An unsecured panel may activate the safety switch, which disconnects power to the system.

Less frequently, a clear monitor might mean you will need to replace your thermostat.

Comfort Unit Won’t Work

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

In the summer, verify you put the thermostat lower than the current temperature. When it’s cold, verify it’s higher. This sounds absurd, but we’ve seen it happen 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 unsecured panel can activate the safety switch, diverting power to the system.

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

“Cool On” or “Heat On” is Flashing

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

Then, check it’s calling for the appropriate equipment to turn on. This is often indicated by “cool on,” “heat on” or an illustration.

If these words or the illustration is pulsing, your thermostat is in a five-minute delay mode. This setting stops your system from bad short cycling. This can occur if you lose power.

Honeywell Thermostat-Specific Error Codes

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

    • 164—Heat pump needs service. Call Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for help.
    • 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 take place.
    • 173—Thermostat temperature sensor error. Reach Lyric technical support at 800-633-3991.
    • 175—AC power restarted. No action needed.
    • 181/182—Replace air filter. Clear the thermostat by tapping “dismiss” after installing a fresh filter.
    • 184—Put in a new humidifier pad. Clear the display by tapping “dismiss” after adding a new pad filter.
    • 185—Put in a new dehumidifier filter. Clear the monitor by touching “dismiss” after putting in a clean filter.
    • 187—Rinse or put in a new ventilator filter. Clear the thermostat by touching “dismiss” after adding a fresh filter.
    • 188/189—Install a new UV bulb. Call Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for support.
    • 210—Register online for exterior temperature. Download the Lyric app to finish this step and ensure correct 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. 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. Use the Lyric app and follow the process to configure your thermostat.

For more information, look at 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. Reach Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for support.
    • 170—Internal memory error. Reach Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for support.
    • 171—Set date and time. Complete these settings so scheduling can run.
    • 173—Thermostat temperature sensor error. Call Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for assistance.
    • 175—AC power restored. No action required.
    • 177—Indoor temperature sensor error. Reach Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for support.
    • 178—Outdoor temperature sensor error. Contact Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for help.
    • 181/182—Get a new air filter. Clear the thermostat by touching “dismiss” after installing a fresh filter.
    • 183—Rinse humidifier tank and replace water filter. Clear the screen by hitting “dismiss” after finishing these steps.
    • 184—Get a new humidifier pad. Clear the display by touching “dismiss” after installing pad filter.
    • 185—Get a new dehumidifier filter. Clear the thermostat by touching “dismiss” after installing a clean filter.
    • 186—Clean ventilator core. Clear the display by tapping “dismiss” after finishing this task.
    • 187—Clean or replace ventilator filter. Clear the screen by tapping “dismiss” after getting a new filter.
    • 188/189—Add a new UV bulb. Get in touch with Service Experts Heating, Air Conditioning & Plumbing at 866-397-3787 for support.
    • 210—Register online for exterior temperature. Use the Lyric app to finish this step and ensure proper 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. 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 up. Use the Lyric app and follow the process to connect your thermostat.

For more details, look at this thermostat’s user manual.

Our Experts are Here to Help

If you’re still having issues after going through the troubleshooting process, our professionals are ready to assist you. Reach us at 866-397-3787 and we’ll come to your house quickly to figure out the issue.

If you have an older thermostat, right now is a great time to consider a new thermostat. Thermostat technology has advanced over the last few years. Ask us for more details on how smart thermostats can make your residence more convenient while helping save on utility expenses all year.

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