Symptoms
- Fan doesn't turn on even in hot weather
- Fan runs continuously regardless of temperature
- Fan makes noise but doesn't move air effectively
Likely causes
- CommonThermostat set too high or malfunctioningMost attic fans use a thermostat to start only above a certain attic temperature.
- CommonA tripped breakerAttic fans are often on their own dedicated circuit.
- PossibleA worn or seized motorAttic environments are hot and dusty, which shortens motor life.
- PossibleA failed belt on belt-driven modelsSome larger attic fans use a belt that can wear out or slip.
What to do
- Check the fan's thermostat setting and lower it temporarily to test if the fan kicks on.
- Check the breaker panel for a tripped breaker on the attic fan circuit.
- If accessible and safe, visually inspect the fan for dust buildup or a visibly loose belt.
- Turn off power before doing any closer inspection in the attic.
- Spin the fan blade by hand with power off to check for a seized motor.
- Replace a worn belt if that's the identified issue on a belt-driven model.
- Call an electrician or HVAC technician if the motor itself needs replacing or the thermostat control is faulty.
Tools and parts
- Flashlight
- Step ladder
Attic fan thermostatSearch: “attic fan thermostat control switch”
When to call a pro
Call an electrician or HVAC technician if the motor, belt, or thermostat needs professional replacement.
Safety
Use caution
Turn off power before working in the attic near the fan, and be cautious of heat and limited space when accessing an attic in summer.