How To Troubleshoot A Ductless Air Conditioner That's Not Working

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You may enjoy your ductless air conditioner because of its simple system that helps cool down just the rooms of your home that you use. However, it is possible for this system to run into a problem that prevents cold air from being made. This simple system will feel as complicated as a car engine as you try to troubleshoot the problem. Here are some tips for figuring out what is wrong with your ductless air conditioning.


Start by investigating a potential electrical problem, since it may be as simple as a blown circuit breaker. Check your electrical panel in your home and verify that the circuit breaker for the ductless air conditioner has not tripped. If it has, flip it back on and see if that fixes the problem.

Air Filter

Do you have air coming out of the unit, but it is not as cold as it once was? This can be due to a clogged filter. Much like with a central air conditioner, all air must pass through the filter before it reaches the inside of your home. If the filter is covered in dirt, then the air can have trouble passing through. Remove the filter and look at its current status. If it's filthy, clean or replace the filter as required by your specific type of ductless air conditioner.

Evaporator Coil

Your ductless air conditioner has evaporator coils that are used to extract heat from the air and cool it down. It is possible for those coils to become frozen, which actually makes the air hot. You may have a chunk of ice in the air conditioner, but the ice is what is preventing the evaporator coils from working.

You'll need to turn the unit off and let the coils naturally defrost on their own. Start the unit up again and see if that fixes the problem. If the coils freeze up once again, then you may have a problem with a lack of refrigerant in the system. You'll need to contact a professional to help identify a potential refrigerant leak and add more of it to the ductless air conditioner.


The unit may not be working due to a faulty thermostat. If the air conditioner cannot accurately read the temperature of the room, that may be what is causing the unit to not kick on when it gets hot. Place a thermometer next to the air conditioner and see the air conditioner and thermometer are reading the same indoor temperature. If there is a big difference, the thermostat will need to be repaired.

If you cannot diagnose the issue of your a/c on your own, reach out to a residential air conditioning repair service.