Why Honeywell Pro Series Thermostat Cool On Is Flashing?

When the HVAC system is actively cooling your house, a ‘cool on’ message will get displayed on the thermostat. But what could make this message start flashing?

A ‘cool on’ message will be flashing on your Honeywell thermostat, in case the system is in delay mode or if the batteries need to be changed; simply wait for 5 minutes or change the batteries and the message will disappear. If the message stays, try resetting the device. 

Why Honeywell Pro Series Thermostat Cool On Is Flashing?

Under normal circumstances, there are two main reasons why your Honeywell thermostat might have a ‘cool on’ message flashing on its display.

  1. The message is there to indicate that a new set of batteries is required. A lot of thermostats do not have a designated battery light, that’s why the devices will use the ‘cool on’ message to alert you that the batteries need to be changed.
  2. Your thermostat might also show you a blinking ‘cool on’ message if the device is in delay mode. This is a safety feature that prevents the system’s compressor from firing up too soon and getting damaged.

If the message disappears once you change the batteries or after 5 minutes (that’s how long the delay mode usually lasts), then you have nothing to worry about.

Read: How To Troubleshoot A Honeywell Zone Damper?

When Will Honeywell Pro Series Thermostat Cool On Start Flashing?

  • When the system is in delay mode (this happens when the system has been turned off and back on too quickly or when you’re switching between ‘cool’ and ‘heat’ mode)
  • When the battery is running low
  • After a power cut
  • When there is an issue with the C-wire

Honeywell Thermostat Cool On Blinking But Not Working

The ‘cool on’ message can also be used to draw your attention to some issues that the system is dealing with. If the message continues flashing for prolonged periods of time and the cooling system is not working, then you should proceed to these troubleshooting steps:

  1. Check the thermostat settings – make sure that you have the correct time set on the thermostat, that it’s in ‘cool’ mode, and that the set temperature is about 5 degrees lower than the current room temperature
  2. Change the batteries – we have already mentioned that the message can start blinking if the thermostat batteries are about to die. Simply insert fresh ones to check, if the issue will get resolved
  3. Ensure that the HVAC system is receiving power – inspect the circuit breaker, check for a blown fuse, make sure that the indoor and outdoor units are on, and check the connections and wires if you feel comfortable doing that
  4. If your air filter is dirty, then change it
  5. If there is such a need, clean the air conditioning coils
  6. Reset the thermostat – make sure to write down your current settings, as resetting the device will erase your preferred schedule

Honeywell Thermostat Flashing Cool On After Changing Batteries

Depending on usage, the batteries in your Honeywell thermostat can last for 8-24 months. If your thermostat model does not have a low-battery indicator, then the device will use the ‘cool on’ message to tell you that the batteries are going to die soon.

Once you have replaced the batteries, the message will continue blinking for a few more minutes. If it isn’t going away, then you can try resetting the thermostat.

Read: Why Does Honeywell Thermostat Go Blank?

Why Does My Thermostat Say Cool On But No Air?

Give the thermostat at least 5 minutes as it looks like it is in delay mode. As soon as this time is up, the HVAC system should start operating.

If nothing has happened even after 10 minutes have passed, then you should:

Have a Question? Ask HVAC Technician

Click here to use the chatbox to speak with one of our technicians.
No in-home service calls. No appointments.

  1. Set the thermostat to the lowest temperature and make sure that the mode is set to ‘cool’.
  2. If your thermostat doesn’t use any batteries, then check the C-wire for any damage.
  3. Make sure that the HVAC equipment is receiving power.
  4. Reset the thermostat.

What to Do If Honeywell Thermostat Is Blinking Cool On?

In the majority of cases, all you would have to do is wait. The cooling system should resume normal operation as soon as 5 minutes pass – this is a safety feature that helps make sure that there is no extra pressure put on the compressor.

How Long Does Cool On Blink?

The ‘cool on’ message will blink for around 5 minutes before disappearing.

If the unit was not in delay mode, then the message can be blinking constantly, and you would have to find the root cause of the problem. 

Read: Why Does Honeywell Thermostat Say Waiting For Equipment?

How Do I Set My Honeywell Proseries Thermostat to Cool?

  1. Press the ‘home’ button.
  2. Press the ‘mode’ button.
  3. Cycle through the available modes and select ‘cool’.
  4. Once you have done that a constant ‘cool on’ message will be displayed. 

Should the Thermostat Be on Auto or On for Cool?

‘Auto’ and ‘on’ are fan settings that control the air-con’s blower. The former means that your fan will turn on only when the system is heating or cooling, while ‘on’ means that the fan will be constantly blowing.

‘Auto’ is usually the preferred setting as, in such a case, your system won’t be using as much energy and the unit would be able to dehumidify the house more effectively.

How Do I Turn on My Honeywell Pro Series AC?

Turn the thermostat on, select the right mode, and set the preferred temperature.

Why Can’t I Change the Temperature on My Honeywell Thermostat?

  • The thermostat is locked
  • The thermostat needs to be reset
  • The lower- or the upper-temperature setting has been reached
  • The batteries are dead
  • The thermostat needs cleaning
  • The thermostat is dead

Why Does Heat Come on When Thermostat Is Cool?

In the majority of cases, a wiring issue is to blame. The wires to the units are either damaged, shortened, or disconnected. 

Read: Why Does Honeywell Thermostat Keep Turning Off?

How Do I Turn the Heat Off on My Honeywell Thermostat?

Press the mode button and select ‘off’ mode. If the thermostat won’t turn the heat off, then you would have to reset the device. 

Does Honeywell Thermostat Automatically Switch Heat and Cool?

Some Honeywell thermostats are equipped with an auto changeover mode that automatically changes between heating and cooling mode when there is such a need. However, no thermostat can switch both ‘heat’ and ‘cool’ simultaneously. 

How Long Should It Take to Cool a House from 80 to 72?

Before assuming that there is something wrong with your thermostat or HVAC unit, make sure to give the equipment enough time to work its magic.

To cool your house from 80 to 72 degrees, for example, an air conditioner would need 2.5 hours on average

Read: Honeywell Humidifier Damper Position On Winter/Summer

How Do You Program a Honeywell Thermostat Pro Series?

Once you have selected the HVAC and fan mode, you can proceed to programming your thermostat to follow a certain schedule

How Do You Reset a Honeywell Pro Series Thermostat?

Sometimes, all you would have to do to get rid of the blinking ‘cool on’ message is reset the thermostat. 

If your thermostat has batteries, then insert those backward for 5 seconds to reset the device. To reboot other Honeywell Pro Series thermostats, you would have to:

  1. Turn the device on.
  2. Press and hold the ‘menu’ button for 5 seconds.
  3. Scroll to the left and select ‘reset’.
  4. You might have to confirm your decision by pressing ‘yes’.