How to Troubleshoot Honeywell Thermostat Errors

Honeywell is one of the top thermostat manufacturers, and we proudly install them on a regular basis in Denver. They’re long-lasting and reliable. In addition, Honeywell is regularly updating its technology, bringing more features for your household.

Still, all thermostats can have errors now and again. Due to this, we’ve put together this useful guide to go over troubleshooting.

While you can typically repair the majority of thermostat problems on your own, they occasionally require Expert support. Our heating and cooling pros are here to help when you need us. We’re only a call away at 303-647-5853.

Let’s start the process by determining what model of thermostat your home has.

What Model of Thermostat Do I Have?

There are three models of thermostats:

  • Manual—This is the typical dial-shaped thermostat. You won’t have error codes with this type, but it’s also the least efficient for saving on heating and cooling bills.
  • Programmable—This thermostat includes a digital screen and arrows you use to determine your desired temperature. You can also use daily programs to reduce the temperature when you’re away and increase it when you come home.
  • Smart—You won’t have to schedule any programs on this thermostat, as it learns your schedule. It automatically adjusts the temperature when you or other household members are away to help you save on utility bills. You can also change the temperature anywhere via your phone or other Wi-Fi-enabled device. 

As is the case with many technologically advanced products, there are common glitches that may happen. Many of these problems don’t call for Expert support and are uncomplicated enough to solve alone.

Common Honeywell Thermostat Issues

All thermostats have a special group of codes matching the malfunctions that occur.

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

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

Display is Blank

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

Next, you should make sure the power is flowing for your furnace or air handler. Verify the switch near the indoor system is switched “on”.

In addition to that, you should make sure all furnace cabinet or air handler doors/panels are tightly secured.

An unsecured panel may activate the safety switch, which stops power to the equipment.

Less frequently, an empty screen may indicate you will need to replace your thermostat.

Comfort System Won’t Run

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

In the summer, verify you set the thermostat beneath the current temperature. In the winter, verify 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 comfirm the cabinet doors or panels are secure on your furnace cabinet or air handler. A loose panel can activate the safety switch, stopping electricity to the unit.

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

“Cool On” or “Heat On” is Flickering

First, ensure your thermostat is on “cool” or “heat.”

Then, make sure it’s calling for the right system to turn on. This is often indicated by “cool on,” “heat on” or an illustration.

If this set of words or the icon is blinking, your thermostat is in a five-minute delay state. This feature keeps your system from damaging short cycling. This could happen if you lose electricity.

Honeywell Thermostat-Specific Error Codes

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

  • 164—Heat pump needs service. Call Service Experts Heating & Air Conditioning at 303-647-5853 for help.
  • 168—Wi-Fi radio error. Reach 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. Call Lyric technical support at 800-633-3991.
  • 175—AC power restored. No action needed.
  • 181/182—Install a new air filter. Clear the screen by tapping “dismiss” after adding a fresh filter.
  • 184—Replace humidifier pad. Clear the screen by touching “dismiss” after adding a clean pad filter.
  • 185—Install a new dehumidifier filter. Clear the monitor by hitting “dismiss” after adding a new filter.
  • 187—Clean or replace ventilator filter. Clear the monitor by tapping “dismiss” after putting in a clean filter.
  • 188/189—Replace UV bulb. Call Service Experts Heating & Air Conditioning at 303-647-5853 for assistance.
  • 210—Register online for exterior temperature. Use the Lyric app to finish this step and ensure accurate thermostat operation.
  • 388—Register online for remote access and exterior temperature. Download the Lyric app to finish 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 select new Wi-Fi network.
  • 508—Wi-Fi not configured. Use the Lyric app and follow the process to connect your thermostat.

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

Honeywell T6 Pro Smart Programmable Thermostat (TH411OU2005) 

  • 164—Heat pump needs service. Reach Service Experts Heating & Air Conditioning at 303-647-5853 for support.
  • 168—Wi-Fi radio error. Reach Service Experts Heating & Air Conditioning at 303-647-5853 for support.
  • 170—Internal memory error. Contact Service Experts Heating & Air Conditioning at 303-647-5853 for assistance.
  • 171—Set date and time. Complete these settings so scheduling can work.
  • 173—Thermostat temperature sensor error. Call Service Experts Heating & Air Conditioning at 303-647-5853 for assistance.
  • 175—AC power reconnected. No action required.
  • 177—Indoor temperature sensor error. Reach Service Experts Heating & Air Conditioning at 303-647-5853 for assistance.
  • 178—Outdoor temperature sensor error. Reach Service Experts Heating & Air Conditioning at 303-647-5853 for help.
  • 181/182—Get a new air filter. Clear the monitor by hitting “dismiss” after putting in a fresh filter.
  • 183—Wash humidifier tank and replace water filter. Clear the screen by touching “dismiss” after completing these procedures.
  • 184—Install a new humidifier pad. Clear the screen by touching “dismiss” after adding a new pad filter.
  • 185—Install a new dehumidifier filter. Clear the display by touching “dismiss” after putting in a new filter.
  • 186—Rinse ventilator core. Clear the display by touching “dismiss” after completing this task.
  • 187—Wash or replace ventilator filter. Clear the monitor by tapping “dismiss” after installing a new filter.
  • 188/189—Get a new UV bulb. Get in touch with Service Experts Heating & Air Conditioning at 303-647-5853 for help.
  • 210—Register online for exterior temperature. Get the Lyric app to complete this step and ensure accurate thermostat operation.
  • 388—Register online for remote access and outside temperature. Use the Lyric app to do 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 select new Wi-Fi network.
  • 508—Wi-Fi not configured. Get the Lyric app and follow the steps to connect your thermostat.

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

Our Experts are Ready to Help

If you’re still running into issues after working through the troubleshooting list, our professionals are available to assist you. Give us a call at 303-647-5853 and we’ll be out rapidly to figure out the problem.

If you use a dated thermostat, today is a great time to consider a replacement. Thermostat technology has come a long way in recent years Ask us for more details on how smart thermostats can make your residence comfier while helping save on utility bills all year.

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