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Air Conditioner Fan Not Working

The part(s) or condition(s) listed below for the symptom Air conditioner fan not working 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.

Most Frequent Causes for Air conditioner fan not working

For the most accurate results, enter your model number.


Cause 1Dual Shaft Fan Motor

The dual shaft fan motor (or circulation fan motor) might be defective. The circulation fan motor has two fan blades: one on either side of the motor. On one side, the fan blade draws in outside air over the condensing coil to dissipate the heat. On the other side, the fan blade directs the air over the evaporator coil. The dual shaft fan motor has bearings that can loosen or bind over time. To determine if the motor bearings are defective, wiggle the motor shaft. If the motor shaft is loose, or if it won’t turn at all, replace the fan motor.

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Cause 2Fan Motor

Try turning the blade by hand. If the blade does not turn freely, this indicates that the motor bearings are worn out. If the motor bearings are worn out, replace the motor. If the blade turns freely, test the incoming power to the fan motor. If power is getting to the fan motor, but the motor won’t run, this also indicates that the motor is defective and should be replaced.

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Cause 3Relay Board

The relay board provides voltage to many components of the air conditioner, including the fan motor. If the relay board isn’t working properly, the fan might not run. Relay boards are often misdiagnosed; before replacing the board, make sure you check more commonly defective parts—particularly the fan motor capacitor and the fan motor itself. If you are certain that all of the other components are working properly, replace the relay board.

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Cause 4Temperature Control Thermostat

The temperature control thermostat has electrical contacts that burn out over time. If the electrical contacts are burned out, the thermostat won’t work properly The fan motor should always be running when the compressor is on. If the compressor is running, but the fan motor is not running, the fan motor or the fan motor capacitor are likely at fault. If both the compressor and the fan motor won’t run, use a multimeter to test the temperature control thermostat 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.)

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Cause 5Thermostat

The thermostat monitors the temperature of the air. When the air temperature rises above a set point, the thermostat activates a switch to provide power to the fan and compressor. If the thermostat is defective, it may prevent the fan from working. To determine if the thermostat is defective, set the air conditioner to cooling and then use a multimeter to test the thermostat for continuity. If the thermostat does not have continuity while the air conditioner is set to cooling, replace the thermostat. (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.)

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Cause 6Main Control Board

The main control board provides voltage to all of the air conditioner’s components. If there is a problem with the control board, it might stop providing power to the fan motor. Control boards are often misdiagnosed; make sure you check more commonly defective parts before replacing the main control board. If you are certain that all of the other components are working properly, replace the main control board.

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Cause 7Thermistor

The thermistor is a sensor connected to the control board that detects the temperature of the air. If the thermistor is faulty, it may prevent the fan from running. To determine if the thermistor is at fault, use a multimeter to test it for continuity. If the thermistor does not have continuity, replace it.

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Cause 8Blower Motor

The blower motor may be burned out or worn out. First, check the fan blades. If the blades don’t spin freely, replace the blower motor. Second, make sure that power is getting to the blower motor. If the blower motor is getting power but the motor still won’t run, replace it. It is not possible to repair the blower motor; if it is defective, you must replace it.

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Cause 9Capacitor

The capacitor is attached to the compressor by electrical leads. If the capacitor burns out, the fan won’t 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.

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Cause 10Rotary Switch

The rotary switch turns to activate the fan motor. Over time, the electrical contacts inside the switch can become pitted, preventing them from conducting electricity. To determine if the rotary switch is conducting electricity, use a multimeter to test the switch for continuity according to your air conditioner’s wiring diagram. If the rotary switch does not have continuity, replace it.

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Cause 11Selector Switch

The selector switch directs voltage to the fan. To determine if the selector switch is at fault, try making selections on the air conditioner’s control board. If the fan runs intermittently after you press a button, replace the selector switch. Additionally, if there is any arcing or smoke coming from the selector switch, replace it.

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