How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the best thermostat brands, and we proudly install them on a regular basis in San Antonio. They’re durable and reliable. Also, Honeywell is regularly updating its technology, offering more features for your house.

Nevertheless, every thermostat can experience problems every now and then. As a result, we’ve compiled this useful handbook to walk you through troubleshooting.

While you can typically fix many thermostat problems alone, they occasionally require Expert support. Our home comfort professionals are ready to support you when you need us. We’re merely a call away at 210-404-4233.

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

What Model of Thermostat Do I Have?

There are three kinds of thermostats:

  • Manual—This is the typical dial-shaped thermostat. You won’t have error codes with this one, but it’s also the least efficient for saving on utility costs.
  • Programmable—This thermostat features a digital screen and arrows you press to determine your desired temperature. You can also set daily programs to decrease the temperature when you’re at work and set it higher when you get back.
  • Smart—You won’t have to make any programs on this thermostat, because it picks up on your schedule. It intuitively changes the temperature when you or loved ones are gone to help you save on energy bills. You can also adjust the temperature anywhere using your phone or other Wi-Fi-enabled device. 

As you know most technologically advanced products, there are common problems that can occur. Many of these problems don’t need pro support and are uncomplicated enough to fix alone.

Common Honeywell Thermostat Problems

Every thermostat has a unique group of codes that correspond to the glitches that happen.

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

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

Display is Blank

If the screen is blank on your programmable thermostat, you may need to replace the batteries. If that doesn’t take care of the malfunction or you rely on a smart thermostat, there might be a wiring malfunction.

Next, you should make sure the power is enabled for your furnace or air handler. Confirm the switch close to the indoor equipment is switched “up”.

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

A panel that isn’t tight may trigger the safety switch, which disconnects power to the system.

Less frequently, an empty monitor can signify you need to install a new thermostat.

HVAC Unit Won’t Run

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

When it’s hot, make sure you set the thermostat lower than the room temperature. In the winter, make sure it’s higher. This sounds goofy, but we’ve seen it take place a lot of times.

Make sure the power switch by your indoor system 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, stopping current to the system.

System still won’t run? Make sure circuit breakers haven’t flipped and that your HVAC system isn’t experiencing error codes.

“Cool On” or “Heat On” is Blinking

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

Then, ensure it’s telling the appropriate unit to start. This is usually indicated by “cool on,” “heat on” or a picture.

If this set of words or the illustration is blinking, your thermostat is in a five-minute delay state. This setting protects your system from damaging short cycling. This may occur if you lose power.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump requires service. Call Aramendia Plumbing, Heating and Air at 210-404-4233 for help.
  • 168—Wi-Fi radio error. Call Lyric technical support at 800-633-3991. 170—Internal memory error. Contact Lyric technical support at 800-633-3991.
  • 171—Set date and time. Complete these settings so scheduling can run.
  • 173—Thermostat temperature sensor error. Reach Lyric technical support at 800-633-3991.
  • 175—AC power restarted. No action required.
  • 181/182—Replace air filter. Clear the monitor by tapping “dismiss” after installing a new filter.
  • 184—Install a new humidifier pad. Clear the display by touching “dismiss” after putting in a clean pad filter.
  • 185—Install a new dehumidifier filter. Clear the display by touching “dismiss” after installing a fresh filter.
  • 187—Wash or put in a new ventilator filter. Clear the screen by hitting “dismiss” after adding a clean filter.
  • 188/189—Install a new UV bulb. Contact Aramendia Plumbing, Heating and Air at 210-404-4233 for assistance.
  • 210—Register online for outside temperature. Download the Lyric app to finish this step and ensure accurate thermostat operation.
  • 388—Register online for remote access and outside temperature. Get the Lyric app to do 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. Download 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. Call Aramendia Plumbing, Heating and Air at 210-404-4233 for help.
  • 168—Wi-Fi radio error. Reach Aramendia Plumbing, Heating and Air at 210-404-4233 for assistance.
  • 170—Internal memory error. Reach Aramendia Plumbing, Heating and Air at 210-404-4233 for help.
  • 171—Set date and time. Finalize these settings so scheduling can operate.
  • 173—Thermostat temperature sensor error. Call Aramendia Plumbing, Heating and Air at 210-404-4233 for assistance.
  • 175—AC power reconnected. No action needed.
  • 177—Indoor temperature sensor error. Call Aramendia Plumbing, Heating and Air at 210-404-4233 for support.
  • 178—Outdoor temperature sensor error. Reach Aramendia Plumbing, Heating and Air at 210-404-4233 for help.
  • 181/182—Replace air filter. Clear the thermostat by tapping “dismiss” after putting in a fresh filter.
  • 183—Rinse humidifier tank and add a new water filter. Clear the thermostat by hitting “dismiss” after doing these tasks.
  • 184—Replace humidifier pad. Clear the display by tapping “dismiss” after installing pad filter.
  • 185—Get a new dehumidifier filter. Clear the display by hitting “dismiss” after installing a fresh filter.
  • 186—Rinse ventilator core. Clear the display by hitting “dismiss” after finishing this task.
  • 187—Wash or install a new ventilator filter. Clear the display by tapping “dismiss” after installing a new filter.
  • 188/189—Get a new UV bulb. Get in touch with Aramendia Plumbing, Heating and Air at 210-404-4233 for support.
  • 210—Register online for outside temperature. Download the Lyric app to finish this step and ensure proper thermostat operation.
  • 388—Register online for remote access and outdoor temperature. Get 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 choose new Wi-Fi network.
  • 508—Wi-Fi not connected. Download the Lyric app and follow the steps to connect your thermostat.

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

Our Experts are Available to Provide Support

If you’re still running into troubles after trying the troubleshooting process, our pros are here to help. Reach us at 210-404-4233 and we’ll come to your house quickly to figure out the issue.

If you use an aging thermostat, today is a good time to think over a replacement. Thermostat technology has advanced in recent years Ask us for more information on how smart thermostats can make your home more comfortable while helping save on utility costs all year.

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