How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the leading thermostat brands, and we proudly install them on a regular basis in Livermore. They’re durable and reliable. Also, Honeywell is regularly advancing its technology, offering more features for your household.

However, every thermostat can experience issues from time to time. As a result, we’ve put together this useful handbook to run through troubleshooting.

While you can usually fix many thermostat troubles alone, they occasionally need Expert assistance. Our HVAC pros are ready to support you when you need us. We’re just a call away at 925-364-5427.

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

What Type of Thermostat Do I Have?

There are three kinds of thermostats:

  • Manual—This is the classic dial-shaped thermostat. You won’t experience error codes with this kind, but it’s also the least efficient for saving on utility bills.
  • Programmable—This thermostat has a digital screen and arrows you use to choose your desired temperature. You can also use daily programs to decrease the temperature when you’re gone and raise it when you get back.
  • Smart—You won’t have to set any programs on this thermostat, because it adjusts to your schedule. It automatically raises and lowers the temperature when you or other household members are gone to help you save on utility bills. You can also raise or lower the temperature anywhere on your phone or other Wi-Fi-enabled device. 

As you know many technologically advanced solutions, there are several problems that can take place. The majority of of these situations don’t require professional assistance and are uncomplicated enough to solve on your own.

Common Honeywell Thermostat Problems

Every thermostat has a special kind of codes assigned to the troubles that take place.

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

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

Display is Blank

If the monitor is blank on your programmable thermostat, you may need to get new batteries. If that doesn’t solve the problem or you rely on a smart thermostat, there might be a wiring issue.

Next, you should check the power is flowing for your furnace or air handler. Make sure the switch near the indoor equipment is in the “on” position.

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

A loose panel may trip the safety switch, which cuts off power to the equipment.

While it’s less common, a blank display can indicate you should replace your thermostat.

Comfort Equipment Won’t Start

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

During warm weather, verify you put the thermostat below the current temperature. When it’s cool, make sure it’s higher. This sounds silly, but we’ve seen it take place a lot of times.

Make sure the power switch near your indoor unit is in the “on” position. You should also check the cabinet doors or panels are secure on your furnace cabinet or air handler. An unsecured panel can activate the safety switch, cutting off power to the system.

System still won’t start? Make sure circuit breakers haven’t flipped and that your HVAC unit isn’t displaying error codes.

“Cool On” or “Heat On” is Flickering

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

Then, ensure it’s signaling the correct equipment to start. This is often indicated by “cool on,” “heat on” or an icon.

If this phrase or the illustration is blinking, your thermostat is in a five-minute delay mode. This feature protects your system from bad short cycling. This could occur if your power is interrupted.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump needs service. Call Service Experts Heating & Air Conditioning at 925-364-5427 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. Complete these settings so scheduling can occur.
  • 173—Thermostat temperature sensor error. Contact Lyric technical support at 800-633-3991.
  • 175—AC power restored. No action needed.
  • 181/182—Install a new air filter. Clear the thermostat by touching “dismiss” after installing a clean filter.
  • 184—Install a new humidifier pad. Clear the display by tapping “dismiss” after adding a fresh pad filter.
  • 185—Put in a new dehumidifier filter. Clear the display by touching “dismiss” after putting in a new filter.
  • 187—Clean or install a new ventilator filter. Clear the monitor by tapping “dismiss” after installing a clean filter.
  • 188/189—Install a new UV bulb. Contact Service Experts Heating & Air Conditioning at 925-364-5427 for help.
  • 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 exterior temperature. Get the Lyric app to do this step and ensure correct 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 procedure to configure your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump requires service. Reach Service Experts Heating & Air Conditioning at 925-364-5427 for help.
  • 168—Wi-Fi radio error. Reach Service Experts Heating & Air Conditioning at 925-364-5427 for help.
  • 170—Internal memory error. Contact Service Experts Heating & Air Conditioning at 925-364-5427 for assistance.
  • 171—Set date and time. Complete these settings so scheduling can operate.
  • 173—Thermostat temperature sensor error. Reach Service Experts Heating & Air Conditioning at 925-364-5427 for support.
  • 175—AC power resumed. No action needed.
  • 177—Indoor temperature sensor error. Contact Service Experts Heating & Air Conditioning at 925-364-5427 for help.
  • 178—Outdoor temperature sensor error. Contact Service Experts Heating & Air Conditioning at 925-364-5427 for help.
  • 181/182—Get a new air filter. Clear the thermostat by tapping “dismiss” after adding a clean filter.
  • 183—Clean humidifier tank and replace water filter. Clear the thermostat by tapping “dismiss” after completing these procedures.
  • 184—Install a new humidifier pad. Clear the screen by hitting “dismiss” after installing pad filter.
  • 185—Install a new dehumidifier filter. Clear the monitor by touching “dismiss” after putting in a fresh filter.
  • 186—Rinse ventilator core. Clear the screen by hitting “dismiss” after doing this task.
  • 187—Rinse or install a new ventilator filter. Clear the display by touching “dismiss” after getting a new filter.
  • 188/189—Add a new UV bulb. Contact Service Experts Heating & Air Conditioning at 925-364-5427 for help.
  • 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 exterior temperature. Download the Lyric app to complete 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 pick new Wi-Fi network.
  • 508—Wi-Fi not set up. Get the Lyric app and follow the procedures to connect your thermostat.

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

Our Experts are Available to Provide Support

If you’re still experiencing problems after going through the troubleshooting process, our professionals are here to help. Give us a call at 925-364-5427 and we’ll come to your house quickly to determine the problem.

If you use an older thermostat, right now is a great time to think about a replacement. Thermostat technology has advanced in recent years Ask us for more info on how smart thermostats can make your house more comfortable while helping save on energy bills all year.

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