To troubleshoot an air conditioner, you must identify the specific problem. Common problems with air conditioners include failing to automatically go on, inadequate cooling, and shutting on and off repeatedly.
If the air conditioner does not go on automatically when the need arises, the thermostat or the power supply to the unit could be the problem. Set the thermostat temperature below the room temperature, then reset any tripped breaker and replace any blown fuses.
If the air conditioner is running but provides inadequate cooling, lower the thermostat by a few degrees, carefully clean the evaporator, and let it run for a few hours. Keep the doors and windows open because high outdoor temperatures affect the effectiveness of an air conditioner.
If the condenser is not working, check the power supply, replace any blown fuses, and reset any tripped circuit breakers. Lower the thermostat temperature by a few degrees and if the problem still persists, engage a professional to check on the motor and the compressor.
If the air conditioner shuts on and off repeatedly, give the entire unit a good cleaning and remove any obstructions, as the cause could be a dirty or a blocked condenser unit, as well as a dirty evaporator.