How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the top thermostat brands, and we proudly install them on a frequent basis in Gaithersburg. They’re long-lasting and trustworthy. In addition, Honeywell is regularly advancing its technology, resulting in more features for your house.

Still, each thermostat can have issues from time to time. As a result, we’ve prepared this valuable manual to go over troubleshooting.

While you can often repair most thermostat problems by yourself, they sometimes need Expert help. Our heating and cooling pros are available to support you when you need us. We’re just a call away at 301-476-4577.

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

What Model of Thermostat Do I Have?

There are three kinds of thermostats:

  • Manual—This is the older dial-shaped thermostat. You won’t experience error codes with this kind, but it’s also the least efficient for lowering utility bills.
  • Programmable—This thermostat has a digital screen and arrows you touch to determine your desired temperature. You can also set daily programs to decrease the temperature when you’re gone and raise it when you come home.
  • Smart—You won’t have to schedule any programs on this thermostat, as it learns your routine. It intuitively raises and lowers the temperature when you or loved ones are gone to help you save on utility bills. You can also change the temperature anywhere on your phone or other Wi-Fi-enabled device. 

As you’re aware many technologically advanced solutions, there are several malfunctions that might take place. Many of these troubles don’t require professional help and are uncomplicated enough to solve by yourself.

Common Honeywell Thermostat Issues

All thermostats have an exclusive group of codes matching the issues that happen.

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

Here are some of the most encountered Honeywell thermostat problems. These apply to the following programmable thermostats:

Display is Blank

If the screen is clear on your programmable thermostat, you might need to replace the batteries. If that doesn’t solve the problem or you use a smart thermostat, there might be a wiring problem.

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

Additionally, you should confirm all furnace cabinet or air handler doors/panels are securely fastened.

A panel that isn’t tight may trigger the safety switch, which cuts off power to the unit.

Infrequently, a clear screen could mean you need to install a new thermostat.

Comfort Equipment Won’t Start

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

When it’s hot, verify you schedule the thermostat beneath the ambient temperature. When it’s cool, make sure it’s higher. This sounds goofy, but we’ve seen it take place many times.

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

Equipment still won’t run? Verify circuit breakers haven’t flipped and that your HVAC unit isn’t experiencing error codes.

“Cool On” or “Heat On” is Flashing

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

Then, ensure it’s telling the right system to start. This is usually demonstrated by “cool on,” “heat on” or an icon.

If this set of words or the illustration is blinking, your thermostat is in a five-minute delay mode. This mode stops your equipment from bad short cycling. This may happen if you lose power.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump needs service. Call Parker Pearce Service Experts at 301-476-4577 for assistance.
  • 168—Wi-Fi radio error. Contact Lyric technical support at 800-633-3991. 170—Internal memory error. Reach 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 resumed. No action necessary.
  • 181/182—Replace air filter. Clear the display by tapping “dismiss” after installing a fresh filter.
  • 184—Replace humidifier pad. Clear the screen by tapping “dismiss” after installing a clean pad filter.
  • 185—Replace dehumidifier filter. Clear the thermostat by hitting “dismiss” after adding a new filter.
  • 187—Rinse or replace ventilator filter. Clear the display by touching “dismiss” after installing a new filter.
  • 188/189—Get a new UV bulb. Contact Parker Pearce Service Experts at 301-476-4577 for assistance.
  • 210—Register online for outdoor temperature. Use 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 complete this step and ensure proper 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 configured. Use the Lyric app and follow the procedure to connect your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump requires service. Call Parker Pearce Service Experts at 301-476-4577 for help.
  • 168—Wi-Fi radio error. Call Parker Pearce Service Experts at 301-476-4577 for support.
  • 170—Internal memory error. Contact Parker Pearce Service Experts at 301-476-4577 for help.
  • 171—Set date and time. Finish these settings so scheduling can work.
  • 173—Thermostat temperature sensor error. Contact Parker Pearce Service Experts at 301-476-4577 for support.
  • 175—AC power resumed. No action necessary.
  • 177—Indoor temperature sensor error. Contact Parker Pearce Service Experts at 301-476-4577 for assistance.
  • 178—Outdoor temperature sensor error. Contact Parker Pearce Service Experts at 301-476-4577 for support.
  • 181/182—Install a new air filter. Clear the screen by tapping “dismiss” after adding a new filter.
  • 183—Clean humidifier tank and replace water filter. Clear the thermostat by hitting “dismiss” after completing these procedures.
  • 184—Install a new humidifier pad. Clear the thermostat by hitting “dismiss” after installing pad filter.
  • 185—Replace dehumidifier filter. Clear the display by hitting “dismiss” after putting in a fresh filter.
  • 186—Clean ventilator core. Clear the display by tapping “dismiss” after doing this task.
  • 187—Rinse or install a new ventilator filter. Clear the display by touching “dismiss” after installing a new filter.
  • 188/189—Install a new UV bulb. Reach Parker Pearce Service Experts at 301-476-4577 for support.
  • 210—Register online for outdoor temperature. Get 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 proper thermostat operation.
  • 399—No Internet. Verify 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 procedures to connect your thermostat.

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

Our Experts are Ready to Help

If you’re still experiencing issues after going through the troubleshooting list, our professionals are here to help. Call us at 301-476-4577 and we’ll arrive rapidly to figure out the problem.

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

Contact Us