Attic Fan Motor Not Working High Speed

Attic fan not turning on.

Attic fan motor not working high speed.

If there is any damage to the belt replace it with a new one. Little or no airflow. If this is not your issue the next thing in line is the high speed relay mounted on the front of the hvac box behind the accumulator. It selects one fan winding for slow or the other for high.

If this fan has a timer and or a variable speed switch repairs are sometimes possible if the fault lies in one of the switches and not the motor. If this doesn t fix the problem a burned out fan motor may need replacing. 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. You can fix this issue by turning down the settings or checking that the fan is getting enough air.

Try tapping on that relay to see if it is stuck. If the motor is working but the fan blades are not moving the problem may be the belt. Other possibilities include damage to the wiring or a switch best repaired by an electrician. Remove the outer casing of the attic fan and check to see if the belt is sagging cracked worn or broken.

Repairs are generally impractical. When running at a high speed setting does the attic fan run hard or sluggishly. Attic exhaust fans power ventilators we usually simply replace the entire unit. Check that a whole house fan is receiving electrical power when it doesn t work at all.

A two speed attic fan should just need a basic toggle switch. These are the common causes. 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. The blower resistor is connected in series to the blower fan motor.

This means that the current running through the blower motor and its speed is therefore controlled by the resistor value. 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 fans can sometimes start making noise whether it s humming rattling or making some other annoying noise. 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.

The user chooses a fan speed by selecting a speed which then connects one of the resistors in the blower resistor pack.