Attic Fan Motor Not Working High Speed

Blower resistors are made of.

Attic fan motor not working high speed.

The user chooses a fan speed by selecting a speed which then connects one of the resistors in the blower resistor pack. A two speed attic fan should just need a basic toggle switch. Other possibilities include damage to the wiring or a switch best repaired by an electrician. Attic fans can sometimes start making noise whether it s humming rattling or making some other annoying noise.

Remove the outer casing of the attic fan and check to see if the belt is sagging cracked worn or broken. The blower resistor is connected in series to the blower fan motor. Repairs are generally impractical. If there is any damage to the belt replace it with a new one.

If the motor is working but the fan blades are not moving the problem may be the belt. 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. These are the common causes. Check that a whole house fan is receiving electrical power when it doesn t work at all.

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. Try tapping on that relay to see if it is stuck. If this doesn t fix the problem a burned out fan motor may need replacing. Attic exhaust fans power ventilators we usually simply replace the entire unit.

This means that the current running through the blower motor and its speed is therefore controlled by the resistor value. When running at a high speed setting does the attic fan run hard or sluggishly. Little or no airflow. Look at the circuit breaker or fuse box to see if a switch has flipped.

You can fix this issue by turning down the settings or checking that the fan is getting enough air. Attic fan not turning on. 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. It selects one fan winding for slow or the other for high.

Does the speed switch look like the silver handle coming out of the plate.