Honeywell Thermostat Flashing Cool On – How to Fix

By Max Anthony •  Updated: 11/27/22 •  8 min read

Honeywell Thermostat Flashing Cool On

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Honeywell thermostat control systems are essential for regulating temperature and reducing your energy bills. But some people are unsure what a thermostat means and what their heating and cooling system is actually doing, like most people don’t understand how thermostats work or what their furnace does.

Honeywell thermostats help you control the heating, ventilation, and air conditioning systems in the house. It’s a small device that shows how warm or cool your home is. It’s normally placed in the attic or next to a window or on one wall in your house.

Honeywell’s thermostat can sense when the temperatures in your home are changing and can turn your air conditioner or heating system off and on in order to control the thermostat setting. When it is one degree cooler or warmer than your thermostat settings, your system heats and cools the rooms to keep the temperature.

If the Honeywell Thermostat says “Cool On”, set the temperature to the absolute lowest setting. After that, just re-install the Honeywell software and see if that changes anything.

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“Cool On” Indicator On Your Honeywell Thermostat

If you see the ‘Coon On’ indicator blink on your Honeywell thermostat, don’t panic. It is as though the indicator will show you when the operation is about to do something.

You will know if the heater is on or not, because when it cycles, it shows that something has been done inside the system unit. When the ‘Cooler On’ blinks while the system is running, there is nothing wrong with that. It will be like normal once it stops operating.

This mode is used to keep the compressor of the HVAC system from being severely affected. When a power loss occurs, the unit may operate normally. It can happen when a unit is powerless, or if the power source in the unit is cut.

How To Identify If There Is A Problem?

But what causes all the fuss? If it just flashes as a safety measure, why do you worry they are going to change it?

Eventually, the cool on indicator will stop flashing when it is flashing for over 5 minutes, and you won’t be able to get cool air out of the HVAC system. This will be a warning sign, and you must do something about it. Here are steps to repair an indicator that continuously flashes Cool on.

Honeywell Thermostat Flashing Cool On

Change the temperature to the lowest possible

What you need to do is to make sure that the thermostat can adjust the temperature or not. Do some adjustments to the thermostat and see if the heating can control the temperature. Now adjust the thermostat to set it to as low as is comfortable, while keeping Cool on, and the fan on. Keep that going for a few minutes. See if the system cools or if there is a noticeable change in the room temperature.

Keep this position for a few minutes and see if you notice any cooling in the room or if you notice a change in the temperature.

Check if Thermostat is in Setup mode

When power goes out, the thermostat automatically switches to set-up mode, causing the ‘Cooling on’ indicator to blink. Check if the temperature setting on your thermostat is not set properly since it will cause this indicator to blink. If this is the case, follow the steps in the manual. If so, read the instructions carefully and follow the steps to save the changes.

Check the batteries

If you lose all the batteries in your thermostat, it won’t work properly. If your thermostat batteries are becoming weak, it’s time to change your batteries. You can use the remaining battery power for 2 to 3 months after the thermostat shows a weak battery status. You should be able to see the battery status on the thermostat.

If your thermostat doesn’t operate through batteries, it uses 24 VAC for operation, and you need to check the wiring in this case. It’s important to shut off the power to the thermostat and check that the thermostat is not causing any problems. You can check the C-wire this way. Sometimes you need to remove the thermostat from its base to check it’s working properly.

Some thermostat display back lights will not work when you replace the batteries.

Check if your HVAC system

Because you may have already tried all the steps in this article and nothing works, you should have more patience. It’s time that you check the HVAC system components and see if they’ve been installed correctly. If they have been installed correctly.

Listen carefully to sounds that could be like a click or a hum, which may be caused by a problem with one of the HVAC system components. It is important that the HVAC components such as the air handlers, furnaces, and air conditioners are working properly. You should make sure that all of them are powered on.

Look for all the electrical connections and make sure they are all good. Make sure that all the switches are on and that the circuit breaker is switched on. Now, check a few things, like whether the door is not open and if any of the components that are in the unit are still attached. Check if there are any obstructions that are preventing the unit from working properly.

It is very important that you switch off the main circuit breaker and start testing all the other electrical components to make sure that they are working correctly. Try turning off all power to the circuit breaker and checking that all the fuses are working. After powering off, check if the fuses are blown by a voltmeter.

Check if the AC filter needs replacing

Even assuming all the HVAC systems in your house are running smoothly, the system will be hampered if the AC filter cannot function properly. When your AC filters are clogged, the unit cannot cool the home properly. The thermostat can be affected as well, and the power bill gets very expensive.

AC filters should be changed every three months because if they aren’t changed, they will eventually become clogged with dust and dirt, which will affect the cooling of your home. If the AC unit is working hard to maintain a comfortable temperature, it will need to work even more hard to cool the room. This puts extra stress on the compressor and the rest of the HVAC equipment.

If your AC isn’t working properly, it may not let you turn on your AC system. When this occurs, you’re going to have a very large temperature drop and problems with other HVAC equipment. The cause is usually due to frozen coils in the pipes or clogging of the registers in the preheater.

Clean the AC coils

AC coil gets really filthy just as easily as a filter does. You might have a problem with one coil that connects to a clogged or dirty one. AC coils get dirty fairly quickly. They become dirty every time the coil is turned on or off. Over months and even years, dust gets on the coil, which then stops the airflow. It cannot absorb heat, and the system will be affected.

If dirt builds up on the coils, you may need to clean them. If you want to get the dirt out of the AC coils, it’s necessary to turn off the unit and also to sweep the area close to it. This will ensure that the coil is not blocked with dirt and that air can flow freely. To make sure that all the air gets to the fan quickly, place the fan in a room that is small and wide.

Reset Your Honeywell Thermostat

When you’re done with the settings on your thermostat, it’s time to unplug it and reset it to its factory settings. This will wipe out all of your data and will allow you to configure the device to do exactly as it did. Take a few notes about how things worked before you reset it.

If you have a Honeywell thermostat, you’ve got to figure out what the model number is of the unit. Depending on the model of the Honeywell thermostat, you’ll need to unplug it if it is connected to a power source such as a circuit wire. If your thermostat has a button that allows you to go to the Menu, just click it and hold it for a few seconds to enable it to be reset. After you have reset the Honeywell thermostat, you can use the same function as before.

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Max Anthony

Mainly Max Anthony is an athletics tutor & lives in Texas but that's not it. He's is also a music producer, content creator, record producer, writer, and session musician. He has been producing music and engineering at a lower level for over 5 years. His passions include quality music gear and that's what he loves to write about on HifiBeast. ( Shoot him an email now )