How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the best thermostat producers, and we proudly install them on a frequent basis in San Antonio. They’re durable and trustworthy. Also, Honeywell is constantly updating its technology, bringing more features for your home.

Still, every thermostat can have problems every so often. As a result, we’ve compiled this informative manual to walk you through troubleshooting.

While you can typically repair many thermostat issues alone, they occasionally require Expert assistance. Our HVAC pros are available to help when you need us. We’re merely a call away at 210-570-9705.

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

What Model of Thermostat Do I Have?

There are three kinds of thermostats:

  • Manual—This is the classic dial-shaped thermostat. You won’t run into error codes with this one, but it’s also the least efficient for saving on energy costs.
  • Programmable—This thermostat has a digital screen and arrows you touch to choose your desired temperature. You can also set daily programs to decrease the temperature when you’re at work and set it higher when you come home.
  • Smart—You won’t have to set any programs on this thermostat, as it learns your routine. It automatically changes the temperature when you or loved ones are gone to help you save on heating and cooling costs. You can also change the temperature anywhere via your phone or other Wi-Fi-enabled device. 

As you know many technologically advanced things, there are common glitches that may take place. The majority of of these problems don’t need Expert assistance and are simple to fix alone.

Common Honeywell Thermostat Issues

Each thermostat has a unique set of codes matching the issues that occur.

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

Here are some of the most encountered Honeywell thermostat issues. These involve the following programmable thermostats:

Display is Blank

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

Next, you should make sure the power is on for your furnace or air handler. Make sure the switch close to the indoor system is in the “on” position.

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

An unsecured panel may trigger the safety switch, which cuts off power to the unit.

Less frequently, a blank monitor may indicate you will need to buy a new thermostat.

Comfort Equipment Won’t Start

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

During warm weather, make sure you schedule the thermostat below the ambient temperature. When it’s cold, make sure it’s higher. This sounds silly, 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 make sure the cabinet doors or panels are tight on your furnace cabinet or air handler. A loose panel can trip the safety switch, diverting power to the system.

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

“Cool On” or “Heat On” is Blinking

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

Then, make sure it’s telling the right equipment to start. This is typically shown by “cool on,” “heat on” or a picture.

If this phrase or the picture is blinking, your thermostat is in a five-minute delay status. This mode protects your system from harmful short cycling. This can take place if you lose power.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump needs service. Call San Antonio Air Service Experts at 210-570-9705 for assistance.
  • 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 occur.
  • 173—Thermostat temperature sensor error. Reach Lyric technical support at 800-633-3991.
  • 175—AC power restarted. No action required.
  • 181/182—Put in a new air filter. Clear the monitor by touching “dismiss” after installing a clean filter.
  • 184—Install a new humidifier pad. Clear the monitor by hitting “dismiss” after installing a clean pad filter.
  • 185—Replace dehumidifier filter. Clear the screen by touching “dismiss” after putting in a fresh filter.
  • 187—Wash or put in a new ventilator filter. Clear the thermostat by touching “dismiss” after adding a fresh filter.
  • 188/189—Replace UV bulb. Ring San Antonio Air Service Experts at 210-570-9705 for help.
  • 210—Register online for outdoor temperature. Use the Lyric app to complete this step and ensure correct thermostat operation.
  • 388—Register online for remote access and outside temperature. Download the Lyric app to complete this step and ensure correct 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 configured. Get the Lyric app and follow the steps to configure your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump must be serviced service. Call San Antonio Air Service Experts at 210-570-9705 for help.
  • 168—Wi-Fi radio error. Reach San Antonio Air Service Experts at 210-570-9705 for help.
  • 170—Internal memory error. Reach San Antonio Air Service Experts at 210-570-9705 for assistance.
  • 171—Set date and time. Complete these settings so scheduling can operate.
  • 173—Thermostat temperature sensor error. Call San Antonio Air Service Experts at 210-570-9705 for help.
  • 175—AC power resumed. No action needed.
  • 177—Indoor temperature sensor error. Call San Antonio Air Service Experts at 210-570-9705 for assistance.
  • 178—Outdoor temperature sensor error. Contact San Antonio Air Service Experts at 210-570-9705 for support.
  • 181/182—Replace air filter. Clear the thermostat by tapping “dismiss” after adding a clean filter.
  • 183—Wash humidifier tank and replace water filter. Clear the display by touching “dismiss” after finishing these procedures.
  • 184—Install a new humidifier pad. Clear the monitor by tapping “dismiss” after getting a new pad filter.
  • 185—Get a new dehumidifier filter. Clear the screen by touching “dismiss” after putting in a clean filter.
  • 186—Wash ventilator core. Clear the monitor by tapping “dismiss” after completing this task.
  • 187—Wash or install a new ventilator filter. Clear the monitor by touching “dismiss” after installing a new filter.
  • 188/189—Get a new UV bulb. Get in touch with San Antonio Air Service Experts at 210-570-9705 for assistance.
  • 210—Register online for exterior temperature. Get the Lyric app to complete this step and ensure proper thermostat operation.
  • 388—Register online for remote access and outdoor temperature. Download the Lyric app to do this step and ensure correct 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. Download the Lyric app and follow the steps to connect your thermostat.

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

Our Experts are Available to Provide Support

If you’re still having problems after trying the troubleshooting steps, our pros are here to support you. Call us at 210-570-9705 and we’ll be out quickly to diagnose the malfunction.

If you rely on an older thermostat, now is a great time to consider a new device. Thermostat technology has come a long way in recent years Ask us for more details on how smart thermostats can make your residence better while helping save on heating and cooling costs year-round.

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