Attic Fan Does Not Run On High Speed

If it is rotating slowly or not producing a lot of air in the high speed setting you may have a problem with the exhaust or intake.

Attic fan does not run on high speed. Attic fans can sometimes start making noise whether it s humming rattling or making some other annoying noise. Some info on the motor is needed. Remove the outer casing of the attic fan and check to see if the belt is sagging cracked worn or broken. For this you can use a 9 v battery a dvm and a 1 megohm resistor from radio shack.

Little or no airflow. If you have leaky ductwork. Homes built after 2015 are required to have all ductwork sealed and tested for airtightness. Check motor current draw and compare with specs.

You can fix this issue by turning down the settings or checking that the fan is getting enough air. Then after checking the capacitor for a short or an open measure its value. Most of those attic fan motors have two motor windings. Your attic fan may not be turning on because of an electrical problem like a tripped circuit breaker a blown fuse or a bad connection.

Check that the blade moves freely. Parts can come loose or erode from high amounts of fan usage while turning the speed up to high can cause a persistent loud hum. Attic fan not turning on. When running at a high speed setting does the attic fan run hard or sluggishly.

If the attic fan isn t turning on it could be an electrical issue a problem with the thermostat or the motor of the fan that s not working. Running the fan when the air conditioner is not on could actually pull the heat out of the attic into the home. Unfortunately homes built before 2015 may have very leaky ducts. High speed and low speed.

Attic fan not running at top speed.