How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the leading thermostat manufacturers, and we proudly install them on a regular basis in Fort Worth. They’re long-lasting and trustworthy. Plus, Honeywell is constantly improving its technology, bringing more features for your family.

Still, all thermostats can have issues occasionally. As a result, we’ve prepared this helpful manual to walk you through troubleshooting.

While you can usually solve most thermostat problems alone, they occasionally call for Expert support. Our heating and cooling professionals are ready to help when you need us. We’re merely a call away at 817-380-5647.

Let’s get started with the process by determining what kind of thermostat your house has.

What Model of Thermostat Do I Have?

There are three models of thermostats:

  • Manual—This is the classic dial-shaped thermostat. You won’t experience error codes with this type, but it’s also the least efficient for reducing heating and cooling expenses.
  • Programmable—This thermostat has a digital screen and arrows you press to set your desired temperature. You can also set daily programs to lower the temperature when you’re away and raise it when you get back.
  • Smart—You won’t have to set any programs on this thermostat, since it learns your routine. It intuitively raises and lowers the temperature when you or loved ones are away to help you save on energy costs. You can also raise or lower the temperature anywhere using your phone or other Wi-Fi-enabled device. 

As you know most technologically advanced products, there are several glitches that may occur. Many of these problems don’t call for Expert help and are simple to fix on your own.

Common Honeywell Thermostat Issues

All thermostats have an exclusive set of codes matching the issues that take place.

Think how simple it can be to repair a computer by restarting it. In many instances, troubleshooting a thermostat can be just as simple.

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

Display is Blank

If the screen is empty on your programmable thermostat, you might need to install new batteries. If that doesn’t fix the malfunction or you have a smart thermostat, there might be a wiring problem.

Next, you should ensure the power is enabled for your furnace or air handler. Verify the switch close to the indoor system is switched “up”.

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

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

Less frequently, an empty screen may signify you should get a new thermostat.

Heating and Cooling System Won’t Turn On

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

During warm weather, verify you schedule the thermostat beneath the ambient temperature. In the winter, make sure it’s higher. This sounds goofy, but we’ve seen it take place lots of times.

Make sure the power switch close to 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 electricity to the system.

System still won’t turn on? Confirm circuit breakers haven’t tripped and that your HVAC equipment isn’t showing error codes.

“Cool On” or “Heat On” is Flickering

To start, confirm your thermostat is set to “cool” or “heat.”

Then, verify it’s signaling the correct unit to turn on. This is often shown by “cool on,” “heat on” or an illustration.

If this phrase or the illustration is flashing, your thermostat is in a five-minute delay state. This setting protects your system from harmful 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 Calverley Service Experts at 817-380-5647 for support.
  • 168—Wi-Fi radio error. Reach 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. Contact Lyric technical support at 800-633-3991.
  • 175—AC power resumed. No action necessary.
  • 181/182—Replace air filter. Clear the screen by touching “dismiss” after adding a clean filter.
  • 184—Replace humidifier pad. Clear the display by tapping “dismiss” after installing a new pad filter.
  • 185—Install a new dehumidifier filter. Clear the monitor by touching “dismiss” after installing a clean filter.
  • 187—Wash or install a new ventilator filter. Clear the screen by touching “dismiss” after putting in a fresh filter.
  • 188/189—Get a new UV bulb. Ring Calverley Service Experts at 817-380-5647 for help.
  • 210—Register online for outside temperature. Get the Lyric app to finish this step and ensure accurate thermostat operation.
  • 388—Register online for remote access and exterior temperature. Use 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 choose new Wi-Fi network.
  • 508—Wi-Fi not set up. Get the Lyric app and follow the process to link your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump needs service. Reach Calverley Service Experts at 817-380-5647 for help.
  • 168—Wi-Fi radio error. Contact Calverley Service Experts at 817-380-5647 for help.
  • 170—Internal memory error. Reach Calverley Service Experts at 817-380-5647 for help.
  • 171—Set date and time. Complete these settings so scheduling can run.
  • 173—Thermostat temperature sensor error. Reach Calverley Service Experts at 817-380-5647 for support.
  • 175—AC power reconnected. No action necessary.
  • 177—Indoor temperature sensor error. Call Calverley Service Experts at 817-380-5647 for assistance.
  • 178—Outdoor temperature sensor error. Reach Calverley Service Experts at 817-380-5647 for support.
  • 181/182—Get a new air filter. Clear the screen by touching “dismiss” after installing a new filter.
  • 183—Rinse humidifier tank and replace water filter. Clear the display by touching “dismiss” after finishing these procedures.
  • 184—Replace humidifier pad. Clear the display by tapping “dismiss” after installing pad filter.
  • 185—Get a new dehumidifier filter. Clear the screen by tapping “dismiss” after installing a new filter.
  • 186—Wash ventilator core. Clear the monitor by hitting “dismiss” after doing this task.
  • 187—Wash or get a new ventilator filter. Clear the screen by hitting “dismiss” after getting a new filter.
  • 188/189—Get a new UV bulb. Get in touch with Calverley Service Experts at 817-380-5647 for help.
  • 210—Register online for outdoor temperature. Get 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 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 select new Wi-Fi network.
  • 508—Wi-Fi not set up. Download the Lyric app and follow the procedures to connect your thermostat.

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

Our Experts are Available to Provide Assistance

If you’re still running into issues after trying the troubleshooting steps, our Experts are ready to support you. Give us a call at 817-380-5647 and we’ll be out as fast as we can to diagnose the problem.

If you have a dated thermostat, right now is a good time to think about a replacement. Thermostat technology has gotten better in recent years Ask us for more information on how smart thermostats can make your home better while helping save on heating and cooling costs throughout the year.

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