How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the best thermostat manufacturers, and we proudly install them on a regular basis in Dallas. They’re long-lasting and trustworthy. In addition, Honeywell is regularly updating its technology, offering more features for your family.

Still, all thermostats can experience problems at times. As a result, we’ve prepared this useful handbook to run through troubleshooting. While Honeywell thermostat troubleshooting problems are rare, they do occur.

While you can typically fix many thermostat issues alone, they occasionally call for Expert help. Our heating and cooling professionals are ready to assist you when you need us. We’re just a call away at 469-250-0932.

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

What Type of Thermostat Do I Have?

There are three types of thermostats:

  • Manual—This is the typical dial-shaped thermostat. You won’t experience error codes with this kind, but it’s also the least efficient for saving on energy costs.
  • Programmable—This thermostat includes a digital screen and arrows you press to choose your desired temperature. You can also choose daily programs to decrease the temperature when you’re at work and increase it when you return.
  • Smart—You won’t have to schedule any programs on this thermostat, because it adjusts to your routine. It automatically changes the temperature when you or loved ones are away to help you save on heating and cooling costs. You can also raise or lower the temperature anywhere on your phone or other Wi-Fi-enabled device.

As you’re aware many technologically advanced solutions, there are regular glitches that may occur. Most of these problems don’t call for pro help and are easy to fix alone.

Common Honeywell Thermostat Troubleshooting Issues

Each Honeywell thermostat has an exclusive group of codes matching the malfunctions that occur.

Think how simple it can be to restore a computer by restarting it. Many times, diagnosing a thermostat can be just as easy.

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

Display is Blank

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

Next, you should ensure the power is enabled for your furnace or air handler. Verify the switch by the indoor equipment is switched “on”.

In addition to that, you should make certain all furnace cabinet or air handler doors/panels are tightly fastened.

An unsecured panel may activate the safety switch, which stops power to the equipment.

Infrequently, an empty display might mean you should install a new thermostat.

Heating and Cooling Unit Won’t Start

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

In the summer, verify you put the thermostat below the current temperature. When it’s cold, verify it’s higher. This sounds goofy, but we’ve seen it happen a lot of times.

Confirm the power switch by your indoor equipment is in the “on” position. You should also make sure the cabinet doors or panels are closed on your furnace cabinet or air handler. A loose panel can activate the safety switch, diverting power to the system.

Heating or cooling still won’t start? Verify circuit breakers haven’t turned off and that your HVAC unit isn’t showing error codes.

“Cool On” or “Heat On” is Blinking

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

Then, check it’s calling for the right equipment to run. This is typically shown by “cool on,” “heat on” or an illustration.

If this phrase or the picture is pulsing, your thermostat is in a five-minute delay state. This setting keeps your equipment from bad short cycling. This can happen if you lose electricity.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump must be serviced. Call Levy & Son Service Experts at 469-250-0932 for help.
  • 168—Wi-Fi radio error. Contact Lyric technical support at 800-633-3991. 170—Internal memory error. Contact Lyric technical support at 800-633-3991.
  • 171—Set date and time. Finalize these settings so scheduling can run.
  • 173—Thermostat temperature sensor error. Contact Lyric technical support at 800-633-3991.
  • 175—AC power restored. No action needed.
  • 181/182—Put in a new air filter. Clear the display by hitting “dismiss” after installing a fresh filter.
  • 184—Install a new humidifier pad. Clear the monitor by touching “dismiss” after installing a clean pad filter.
  • 185—Put in a new dehumidifier filter. Clear the thermostat by touching “dismiss” after installing a fresh filter.
  • 187—Wash or replace ventilator filter. Clear the thermostat by hitting “dismiss” after adding a fresh filter.
  • 188/189—Install a new UV bulb. Ring Levy & Son Service Experts at 469-250-0932 for help.
  • 210—Register online for exterior temperature. Download the Lyric app to do this step and ensure correct thermostat operation.
  • 388—Register online for remote access and exterior temperature. Download the Lyric app to do 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 choose new Wi-Fi network.
  • 508—Wi-Fi not set up. Download the Lyric app and follow the process to configure your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005)

  • 164—Heat pump requires service. Contact Levy & Son Service Experts at 469-250-0932 for help.
  • 168—Wi-Fi radio error. Contact Levy & Son Service Experts at 469-250-0932 for help.
  • 170—Internal memory error. Contact Levy & Son Service Experts at 469-250-0932 for help.
  • 171—Set date and time. Finalize these settings so scheduling can work.
  • 173—Thermostat temperature sensor error. Contact Levy & Son Service Experts at 469-250-0932 for help.
  • 175—AC power resumed. No action necessary.
  • 177—Indoor temperature sensor error. Contact Levy & Son Service Experts at 469-250-0932 for help.
  • 178—Outdoor temperature sensor error. Contact Levy & Son Service Experts at 469-250-0932 for help.
  • 181/182—Get a new air filter. Clear the thermostat by hitting “dismiss” after adding a clean filter.
  • 183—Rinse humidifier tank and install a new water filter. Clear the thermostat by touching “dismiss” after finishing these steps.
  • 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 display by hitting “dismiss” after adding a clean filter.
  • 186—Rinse ventilator core. Clear the thermostat by touching “dismiss” after completing this task.
  • 187—Rinse or replace ventilator filter. Clear the monitor by hitting “dismiss” after getting a new filter.
  • 188/189—Add a new UV bulb. Reach Levy & Son Service Experts at 469-250-0932 for help.
  • 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 outside temperature. Download 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 choose new Wi-Fi network.
  • 508—Wi-Fi not connected. Download the Lyric app and follow the process to connect your thermostat.

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

Our Experts are Here to Provide Support

If you’re still running into issues after going through the troubleshooting process, our professionals are ready to assist you. Reach us at 469-250-0932 and we’ll arrive rapidly to figure out the problem.

If you use an aging thermostat, today is a great time to think about a new thermostat. Thermostat technology has gotten better lately Ask us for more details on how smart thermostats can make your home better while helping save on energy bills all year.

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.