How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the leading thermostat brands, and we proudly install them on a regular basis in Belleville. They’re long-lasting and dependable. Also, Honeywell is constantly updating its technology, bringing more features for your family.

However, all thermostats can have troubles now and again. That’s why we’ve prepared this valuable handbook to run through troubleshooting.

While you can usually fix most thermostat issues by yourself, they sometimes need Expert assistance. Our HVAC pros are available to help when you need us. We’re only a call away at 613-707-2421.

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

What Model of Thermostat Do I Have?

There are three types of thermostats:

  • Manual—This is the typical dial-shaped thermostat. You won’t run into error codes with this one, but it’s also the least efficient for reducing utility costs.
  • Programmable—This thermostat features a digital screen and arrows you touch to choose your desired temperature. You can also choose daily programs to lower the temperature when you’re away and increase it when you come home.
  • Smart—You won’t have to set any programs on this thermostat, because it adjusts to your routine. It instinctively changes the temperature when you or family members are out and about to help you save on energy expenses. You can also change the temperature anywhere via your phone or other Wi-Fi-enabled device. 

As you know many technologically advanced products, there are several glitches that may take place. Most of these troubles don’t need pro help and are uncomplicated enough to repair by yourself.

Common Honeywell Thermostat Issues

All thermostats have a unique set of codes that correspond to the troubles that occur.

Think how easy it can be to restore a computer by restarting it. In many instances, diagnosing a thermostat can be just as simple.

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

Display is Blank

If the screen is blank on your programmable thermostat, you could need to get new batteries. If that doesn’t fix the malfunction or you have a smart thermostat, there may be a wiring malfunction.

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

Also, you should make sure all furnace cabinet or air handler doors/panels are securely in place.

A loose panel may trip the safety switch, which disconnects power to the system.

While it’s less common, an empty display can indicate you should install a new thermostat.

Comfort Unit Won’t Work

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

In the summer, verify you schedule the thermostat lower than the ambient temperature. When it’s cool, confirm it’s higher. This sounds goofy, but we’ve seen it take place many times.

Ensure the power switch close to your indoor unit is in the “on” position. You should also comfirm the cabinet doors or panels are secure on your furnace cabinet or air handler. An unsecured panel can trip the safety switch, diverting electricity to the equipment.

System still won’t run? Confirm circuit breakers haven’t flipped and that your HVAC unit isn’t showing error codes.

“Cool On” or “Heat On” is Flashing

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

Then, make sure it’s calling for the appropriate system to run. This is usually demonstrated by “cool on,” “heat on” or a picture.

If these words or the icon is flashing, your thermostat is in a five-minute delay status. This setting 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 requires service. Call D & K Heating Service Experts at 613-707-2421 for support.
  • 168—Wi-Fi radio error. Call Lyric technical support at 800-633-3991. 170—Internal memory error. Reach Lyric technical support at 800-633-3991.
  • 171—Set date and time. Complete these settings so scheduling can run.
  • 173—Thermostat temperature sensor error. Call Lyric technical support at 800-633-3991.
  • 175—AC power restored. No action necessary.
  • 181/182—Replace air filter. Clear the screen by tapping “dismiss” after adding a clean filter.
  • 184—Replace humidifier pad. Clear the screen by hitting “dismiss” after adding a new pad filter.
  • 185—Put in a new dehumidifier filter. Clear the display by tapping “dismiss” after adding a fresh filter.
  • 187—Rinse or put in a new ventilator filter. Clear the monitor by hitting “dismiss” after installing a fresh filter.
  • 188/189—Get a new UV bulb. Call D & K Heating Service Experts at 613-707-2421 for assistance.
  • 210—Register online for outside temperature. Get the Lyric app to do this step and ensure accurate thermostat operation.
  • 388—Register online for remote access and outdoor temperature. Download 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 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 information, see this thermostat’s user manual.

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump requires service. Reach D & K Heating Service Experts at 613-707-2421 for help.
  • 168—Wi-Fi radio error. Contact D & K Heating Service Experts at 613-707-2421 for help.
  • 170—Internal memory error. Contact D & K Heating Service Experts at 613-707-2421 for assistance.
  • 171—Set date and time. Finish these settings so scheduling can work.
  • 173—Thermostat temperature sensor error. Reach D & K Heating Service Experts at 613-707-2421 for assistance.
  • 175—AC power reconnected. No action required.
  • 177—Indoor temperature sensor error. Contact D & K Heating Service Experts at 613-707-2421 for help.
  • 178—Outdoor temperature sensor error. Contact D & K Heating Service Experts at 613-707-2421 for assistance.
  • 181/182—Install a new air filter. Clear the display by hitting “dismiss” after installing a clean filter.
  • 183—Wash humidifier tank and replace water filter. Clear the display by hitting “dismiss” after finishing these tasks.
  • 184—Get a new humidifier pad. Clear the monitor by tapping “dismiss” after installing pad filter.
  • 185—Replace dehumidifier filter. Clear the display by touching “dismiss” after putting in a new filter.
  • 186—Wash ventilator core. Clear the monitor by tapping “dismiss” after completing this task.
  • 187—Rinse or get a new ventilator filter. Clear the screen by hitting “dismiss” after installing a new filter.
  • 188/189—Add a new UV bulb. Reach D & K Heating Service Experts at 613-707-2421 for assistance.
  • 210—Register online for exterior temperature. Get the Lyric app to complete this step and ensure correct thermostat operation.
  • 388—Register online for remote access and exterior temperature. Get the Lyric app to complete this step and ensure proper thermostat operation.
  • 399—No Internet. Confirm 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. Get the Lyric app and follow the procedures to connect your thermostat.

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

Our Experts are Here to Provide Support

If you’re still running into issues after trying the troubleshooting process, our professionals are available to support you. Call us at 613-707-2421 and we’ll be out quickly to diagnose the problem.

If you have an older thermostat, today is a great time to think about a replacement. Thermostat technology has come a long way over the last few years. Ask us for more info on how smart thermostats can make your residence more convenient while helping save on utility expenses throughout the year.

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