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Honeywell thermostat not cooling

Honeywell thermostat not cooling. Honeywell thermostats are the most popular thermostat in the market, allowing you to control room temperature at the lowest electricity cost. Although the Honeywell thermostat is a reliable tool, but sometimes it induces problems.

Are your Honeywell thermostat not functioning correctly? It is quite annoying and unbearable when the Honeywell thermostat is not cooling the home properly, especially during the hottest summer days.

I can feel your pain. That’s why I have made a helpful guide for you to solve your thermostat not cooling problem even when the indicator shows it’s working.

In this article, I will give you a detailed look at the reasons and solutions for thermostat problems.

Honeywell thermostat not cooling

Honeywell thermostat not cooling 2023

Every problem comes with a solution. The Honeywell AC unit is not delivering cold air into your room because of the low refrigerant levels, dirty air filters, faulty evaporator coil, improper functioning of the compressor, weak batteries, and incorrect settings.

Let’s start to discuss the reasons, along with the best solutions, for why your Honeywell thermostat is not blowing the cold air into the home.

Reason 1: Dirty Air Filters and Coils

The dirty air filters and outdoor coils of the AC are the main reason for your Honeywell thermostat not working when you turn it on. When dirt and debris accumulate in the air conditioner’s filter, it restricts the cold air from passing through the room because it clogs the filters.

Dirty fan blades and clogged filter decreases the cooling capacity of HVAC. Uncleaned air filters and dirty coils create more noise than usual.


You should clean the air conditioner filters monthly to remove dirt and debris. The air filters and AC coils are easily cleaned by rinsing them with a hose.

Also, check the air filters of the thermostat to a technician every year. The cleaned air filters and fan blades circulate the cool air efficiently.

If needed, replace your air filters with a new air filter according to the size and type of your AC system. You can replace the Honeywell AC air filters by following the step-by-step instructions:

  • First, Power Off the AC unit as a safety measure by unplugging or switching off the circuit breaker.
  • Wear gloves and remove the old dirty air filters that are located in the air handler.
  • Install the new air filters in their place correctly.
  • Turn the Power On by plugging the unit back in.

Reason 2: Low Refrigerant Levels

Low Refrigerant Levels

When your AC is running but not cooling the house, it may be due to the low refrigerant levels.

As you know, refrigerant is a chemical substance in the air conditioner that supplies cool air throughout the living area.

But if the refrigerant levels decrease than the standard requirement, it stops the AC from functioning correctly.

The refrigerant levels get low because leakage occurs in the small holes of AC pipes.


You should check the pressure refrigerant of the AC system by comparing it with company specifications. If you notice leakage in the pipes, repair it and refill the refrigerant in the system. Remember, it is a time-consuming and costly process.

Reason 3: Incorrect Wiring

A wrong thermostat wiring also affects your Honeywell thermostat’s cooling and heating functionality.

For example, when you use a Honeywell thermostat for the first time and you mistakenly connect the W and Y wires reversely. So, loose or incorrect wiring causes your thermostat not to turn on the AC.


Make sure you attach the wires’ terminals of the thermostat correctly to the wall plate. If you want help, contact a professional HVAC repairer. I suggest you don’t mix the wire terminals to prevent the issue.

Reason 4: Low or Faulty Thermostat Batteries

Low or Faulty Thermostat Batteries

The low thermostat batteries are another reason for the Honeywell thermostat not cooling down the room.

A low battery alert on the screen does not turn ON the AC and halts cooling in the apartment.


If your Honeywell thermostat screen indicates low battery status and displays a black screen or if the screen demonstrates “No power source,” it means the battery is faulty. You can fix it quickly by replacing the Honeywell thermostat battery with the new battery.

Consider the below steps to change your thermostat’s battery:

  • Take out the thermostat from the wall carefully.
  • Open the side where the batteries are placed and remove the old batteries.
  • Then insert the new battery in its place and close it tightly.
  • Fix your Honeywell thermostat on the wall.

Reason 5: A Wrong Settings

When your thermostat is not set on the cool mode, it stops flowing the cool air in your room. Wrong thermostat settings can also be the reason for the Honeywell to function accurately.


You must ensure the right settings of the thermostat. It is essential to check the thermostat is in cool mode by looking at the “snowflake icon” or a “cool on” message on the displaying screen. Set the temperature in the thermostat according to your body’s needs.

Reason 6: Furnace Door Not Closed

Furnace Door Not Closed

Another main reason for the Honeywell thermostat not changing the room temperature is the open furnace door. It will not supply the cool air in your room and stay in the AC.


Make sure that the furnace door of the air conditioner is securely closed and the furnace power switch is ON to enjoy the proper cooling function of the AC.

Final Thoughts

So that’s how to troubleshoot a Honeywell thermostat that doesn’t cool the lounge and rooms perfectly. Hopefully, you can now wisely resolve the thermostat issue with my tips and saves your mechanic cost. I confidently suggest you clean the outdoor air filters and coils monthly. If your Honeywell thermostat problem persists, you should check it to the HVAC expert.

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