Honeywell Thermostat Cool On Not Working: Easy Fix - Robot Powered Home (2023)

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When I first got my Honeywell thermostat, one of the things that caught my eye was the ‘Cool On’ indicator that kept flashing on my thermostat’s display.

Since I had never used a Honeywell thermostat before, this message had me scratching my head, wondering what the thermostat was trying to tell me.

It reminded me of the time I faced connection issues with my Honeywell Thermostat.

After some online research and reading the user manual, I eventually figured out what this message meant.

Like the other operation modes offered by your Honeywell Thermostat, the’ Cool On’ indicator lets you know that the thermostat has begun to work within your HVAC system.

It is simply a safety measure built into the system to protect the compressor from damage in the event of a power surge.

However, if your Honeywell thermostat has been blinking for more than 5 minutes and you still cannot feel any cooling, resetting the thermostat can fix the issue.

In this article, I discuss the different steps you can take to resolve the issues with ‘Cool On’ on your Honeywell thermostat and explain the different problems that may have caused this problem.

Steps To Troubleshoot Issues With ‘Cool On’: Honeywell Thermostat

The ‘Cool On’ indicator flashing on your Honeywell thermostat should normally resolve itself within 5 minutes.

However, if that does not happen, you can use the steps below to troubleshoot the issue and resolve the problem.

Set Thermostat To Lowest Temperature Setting

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Set your thermostat to the lowest temperature reading while making sure the mode is set to Cool.

Also, make sure that the fan setting is set to Auto, especially if your Honeywell Thermostat says cool on but no air seems to come out. Doing this will let you check if your thermostat can reliably control the cooling within your home.

Leave it at the lowest setting for a while and try to observe for any changes in the temperature.

You can also try setting different temperatures to see if your thermostat is giving the right calls for cooling.

If everything works as expected, it means that your thermostat is working perfectly and that the issue might be within the HVAC system.

However, if the problem is with the thermostat, you try some of the fixes mentioned below in the list.

Check If Thermostat Is In Setup Mode Or If The Clock Is Set

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A sudden power outage can cause your thermostat to revert to setup mode.

In some cases, this can cause the ‘Cool On’ indicator on your thermostat to begin blinking.

If this is the issue, simply complete the setup, and the issue will resolve on its own.

Also, make sure to check the clock on your thermostat and make sure that it is turned on and set correctly.

Check The Thermostat Batteries

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Another possible cause is low battery. If the thermostat’s batteries are low, it will not be able to begin heating or cooling.

To know if this is the problem, check your thermostat’s display for a ‘Battery Low’ indicator.

Honeywell thermostats, on average, can function for about two months before they begin to display this.

If your thermostat works on 24 VAC and not batteries, you need to check the wiring inside your thermostat.

To do this, power down the system, detach the thermostat, unscrew it and check the C-wire for any damage.

If you’ve installed your Honeywell Thermostat without a C-wire, replace your batteries.

I’ve put together a comprehensive guide on replacing Honeywell Thermostat Batteries.

Check If Air Handler/Fans, Furnace, And AC Unit Have Power

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If none of the steps above resolved your problem, it might be time to turn your focus away from the thermostat and onto your HVAC system.

Check your equipment and make sure they have been plugged in properly with all the switches turned on.

Inspect the different power supplies, connectors, sockets, etc., for any signs of damage.

You can also check the components on your equipment and make sure that there are no loose or unscrewed parts.

Ensure nothing is blocking your equipment and listen for any unusual humming or clicking noises that can indicate some problem with the unit.

Another area to check for potential issues is the circuit breakers. You can try turning your equipment off and on, both directly and at the circuit breakers. You can also check for blown fuses.

Check Indoor AC Filter And See If It Needs Changing

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The indoor AC filter tends to collect dirt very quickly.

When the filter is clogged and dirty, it causes your AC unit to consume more power because it needs to work harder and increases your AC breaking down.

If your AC filter is not in good condition, it doesn’t just affect the quality of the air you breathe but also the rest of your HVAC equipment, your thermostat, and your power bill as well.

It is recommended that you change your AC filter every three months to ensure that your AC works optimally.

Check AC Coils And See If They Are Dirty

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Like the indoor AC filter, you also have to check for blocked or dirty external AC coils.

These coils tend to collect dirt over the months and years of operation, which can disrupt the airflow.

If the coils are dirty, your AC will not be able to heat or cool the air as well as it did before.

Check your AC’s coils to see if there is any buildup on them. If you do need to clean them, make sure to turn off the main unit before cleaning out the coil.

In addition to this, you can also try cleaning the area around the AC and give it enough space from its surroundings to ensure that the airflow is unaffected.

Reset Your Thermostat

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If you are still unable to resolve the issue after checking for possible issues with your thermostat and inspecting your equipment for any possible defects, there is one solution left to try.

You can reset your thermostat to its factory default settings. However, doing so will mean that you wipe away all the settings and programs configured into your thermostat.

So make sure you make a note of all the configurations you need before you proceed to reset your thermostat.

The steps you need to follow to reset your thermostat vary depending on your own model.

If your model has the ‘Menu’ button, you can either press or press and hold the button until you get the options ‘Reset’, ‘Factory’, or ‘Factory Reset’.

In some models, you can find the ‘Menu’ option under ‘Preferences’. If you are unsure how to reset your thermostat, you can search online for your own model.

If your Honeywell thermostat is powered via the C-wire, make sure you turn off the power before you perform the reset, just to be safe.

Once you have successfully reset your Honeywell thermostat, you can restore your previous configurations and continue using it as usual.

Call Honeywell Support

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If none of these solutions were able to resolve your issue, the last option left for you to try is to contact Honeywell’s Customer Support.

Make sure to explain to them all the different steps you took to troubleshoot the issue, as this will help them diagnose your problem quickly and aid you in resolving the issue.

Final Thoughts on “Cool On” on your Honeywell Thermostats

Ensure that when “Cool On” is activated, the furnace door is securely closed and that the power switch on the furnace is set to On.

Also, make sure the circuit breaker switches for the furnace are on.

You May Also Enjoy Reading:

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  • Honeywell Thermostat Flashing “Return”: What Does It Mean?
  • Honeywell Thermostat Wait Message: How To Fix It?
  • Honeywell Thermostat Permanent Hold: How And When To Use

Frequently Asked Questions

Does the Honeywell thermostat have a reset button?

Most Honeywell thermostats use the ‘Menu’ option as the reset button. Pressing and holding the ‘Menu’ option displays different reset options. Some older thermostat models even use the fan button as a reset button.

How do you reset a Honeywell thermostat when it is locked?

If your Honeywell thermostat is locked, you need to unlock it first before you can proceed to reset it.

To unlock your Honeywell thermostat, press the center button from the lock screen. Then, enter the passcode that you set. The default code is 1234.

Once you type in the code and press ‘Select’, your thermostat will unlock, and you can proceed to reset it.

What does permanent hold on the Honeywell thermostat mean?

The permanent hold feature on your Honeywell thermostat allows you to override your programmed schedule to set a temperature for an indefinite period of time manually.

To enable this feature, you have to toggle the temperature and either press hold or press and hold the button until a message appears, depending on your model.

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