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HomeRepair HelpA/C RepairAir conditioner not cooling Repair
Air conditioner not cooling
If your air conditioner is not cooling, blowing warm air, or just not getting cold enough, start with the parts that most often reduce airflow or keep the unit from calling for proper cooling. A clogged air filter is the most likely cause because it restricts airflow and can make the evaporator coil frost over, cutting cooling capacity fast. If the filter is clean, the user control and display board may not be letting you set or maintain the correct temperature. Dirty condenser coils are another common reason an AC is not cooling, since built-up debris prevents the coils from releasing heat and can make the compressor run continuously. A failed dual run capacitor can keep the compressor or fan motor from running, while a bad compressor is possible but should be checked only after the overload protector and capacitor have been tested. A faulty thermistor can also cause an air conditioner temperature control problem by sending the wrong air-temperature reading to the control board. Enter your model number on RepairClinic.com to find the exact replacement part for your specific air conditioner.
01 - Air Conditioner Air Filter
If the air filter is clogged, air cannot flow properly through the air conditioner. This greatly reduces the cooling capacity of the air conditioner. In addition, if the air filter is clogged, the evaporator coils will frost over. Most air filters used in stand-alone air conditioners can be cleaned with soap and water. Only filters that are extremely clogged with debris or damaged will need to be replaced.
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Top Solution
02 - Air Conditioner User Control and Display Board
The user control and display board allows the user to operate the unit by selecting fan speeds and cooling temperatures. If the board is defective, it may not allow the unit to be set to a proper cooling temperature. If the temperature sensor or thermistor tests appropriately with a multimeter, it's possible the user control and display board is malfunctioning and will need to be replaced.
Top Solution
03 - Condenser Coils are Dirty
The condenser coils dissipate the heat as the refrigerant passes through the coils. If the condenser coils are dirty, they won’t be able to dissipate the heat as effectively. As debris builds up on the coils, the air conditioner will become less efficient, causing the air conditioner to work harder to cool down. If the coils are significantly dirty, the air conditioner will not be able to maintain the proper temperature, and the compressor will run continuously in an attempt to cool the room. Check the condenser coils to determine if they are dirty. Refer to owner's manual for cleaning instructions.
Top Solution
04 - Air Conditioner Dual Run Capacitor
A dual run capacitor will power both the compressor and the fan motor. If the capacitor burns out, the compressor or fan motor will not run. To determine whether the capacitor is burned out, use a multimeter to test it for continuity. If the capacitor does not have continuity, replace it.
Highly Likely
05 - Air Conditioner Compressor
The compressor might be defective. However, this is not usually the case. Before replacing the compressor, be sure to check more commonly defective components—particularly the overload protector and the compressor capacitor. If the compressor is defective, it should only be replaced by a licensed technician.
Highly Likely
06 - Air Conditioner Thermistor
The thermistor is a sensor connected to the control board that detects the temperature of the air. The resistance value of the thermistor changes in conjunction with the air temperature. If the air temperature rises, the resistance value will decrease. To determine if the thermistor is at fault, use a multimeter to test it for continuity. If the thermistor does not have continuity, or if the resistance of the thermistor does not change with a change in temperature, replace the thermistor. (To find specific temperature and resistance values, try checking your user’s manual.)
Common
07 - Air Conditioner Condenser Fan Motor
To determine if the condenser fan motor is working, use a multimeter to test the incoming voltage to the motor. If the condenser fan motor is receiving the correct voltage, but the motor still won’t run, you should inspect the capacitor, if applicable, for any bulging or leaking. You can also use a multimeter to determine if the capacitor can hold and release its charge. If the capacitor appears to be in good condition, replace the condenser fan motor.
Common
Frequently Asked Questions
Why is my air conditioner not cooling even though it is running?
What causes an air conditioner to blow warm air?
Why are my AC coils frozen and the room still is not getting cold?
Why does my air conditioner compressor run constantly but not cool well?
How do I find the right air conditioner part for my repair?