The part(s) or condition(s) listed below for the symptom Air conditioner not cooling are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.
Air Conditioner Won't Turn Off? Air Conditioner Troubleshooting
Air Conditioner Remote Not Working? Air Conditioner Troubleshooting
Air Conditioner Loud or Noisy? Air Conditioner Troubleshooting
Air Conditioner Fan Not Working? Air Conditioner Troubleshooting
Air Conditioner Compressor Won't Run? Air Conditioner Troubleshooting
Air Conditioner Not Cooling? Air Conditioner TroubleshootingIf 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. To remove debris from the air filter, try cleaning the filter. If it is not possible to clean the air filter, replace it.
User Control and Display Board
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. If the condenser coils are dirty, clean them.
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.
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.
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.)
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.
The control board regulates the voltage to the compressor and the fan motor. If the control board fails, some components will not function properly or will not work at all. Control boards are often misdiagnosed; make sure to check more commonly defective parts first before replacing the control board.
The temperature control thermostat is a sensor which monitors the temperature of the air and activates a switch to provide power to the fan and compressor when the air temperature drops below a set point. If the thermostat isn’t working, the air conditioner will cool continuously or won’t cool at all. To determine if the temperature control thermostat is defective, use a multimeter to test it for continuity. If the thermostat does not have continuity, replace it. (Note: Some thermostats may also control a heater and, as a result, will have three terminals. Refer to your air conditioner’s wiring diagram for more information.)
The main control board regulates the voltage to the compressor and the fan motor. If the main control board fails, some components will not function properly or will not work at all. Main control boards are often misdiagnosed; make sure to check more commonly defective parts first before replacing the main control board.
The run capacitor is connected to the compressor with electrical leads. If the run capacitor burns out, the compressor will not run. To determine if the run capacitor is burned out, test the capacitor using a multimeter. If the capacitor does not have continuity, replace it.
An air conditioner dual shaft fan motor is the component that spins both the condenser fan blade in the rear of the unit and the fan blade that forces the cooled air out the front vent. If the fan motor is burned out, the air won't be circulated and the unit will be unable to cool. You can use a multimeter to determine if power is reaching the fan motor. If power is reaching the motor, but it doesn't run, the component will need to be replaced.
An air conditioner fan motor is the component that spins the fan blade or blower wheel to circulate the air. If one of the fan motors is burned out, the air won't be circulated and the unit will not cool properly. You can use a multimeter to determine if power is reaching the fan motor. If power is reaching the motor, but it doesn't run, the component will need to be replaced.
