Step 1 test the fan motor.
How to test attic fan thermostat.
Turn the attic fan off and unplug the motor from the thermostat.
Locate the thermostat casing and open it using a screwdriver.
Note down the wiring before proceeding to remove it.
Step 2 test the thermostat.
Also note down the power rating and the fan capacity in cubic feet per minute.
Note down the temperature settings for later reference.