What causes the outdoor fan on AC stops running?

1. Thermostat Setting: Check if your thermostat is set to "Auto" mode. If it's set to "On," the fan will run continuously, regardless of the temperature.

2. Power Supply: Ensure the outdoor unit is receiving power. Check the circuit breaker or fuse associated with the air conditioner and make sure it's turned on or not blown.

3. Fan Motor: The outdoor fan motor may be defective or have a loose connection. Listen closely to hear if there's a humming sound coming from the unit. If you don't hear a humming sound, it could indicate a problem with the fan motor.

4. Capacitor: The capacitor provides a boost of power to start the fan motor. If the capacitor fails, it can prevent the fan from running.

5. Compressor Overload: If the compressor encounters a problem or is overloaded, it can cause the entire unit, including the fan, to shut off as a safety measure.

6. Refrigerant Level: Low refrigerant levels can lead to various problems, including the outdoor fan not running.

7. Contactor: The contactor is a switch that controls the flow of power to the outdoor unit. A faulty contactor can prevent the fan from receiving power.

8. Wiring Issues: Loose or damaged wiring connections between the outdoor unit and the thermostat can also cause the fan to stop running.

9. Control Board: The control board is the brain of the air conditioning system. A malfunctioning control board can affect the operation of various components, including the outdoor fan.

If you're not comfortable troubleshooting and repairing an air conditioner, it's recommended to contact a qualified HVAC technician to diagnose and fix the issue.