Monday, December 14, 2015

The trouble with bathroom exhaust fans – troubleshooting your bathroom exhaust fan

Bathroom exhaust fans provide a vital function to the indoor air quality of the home by exhausting odors and moisture that can cause mold or mildew to grow. But they are only effective if they are working. There are many reasons that exhaust fans might start to have issues or stop functioning all together. The good news is not all of them mean you need to replace the entire fan. Here are a few troubleshooting tips:

CAUTION: Before starting any maintenance make sure the fan is turned off at the circuit board.

If the fan has completely stopped operating:
Check to see if there is power to the fan. A circuit might be tripped. Next, see if the motor plug is connected. Typically fans will have a plug running from the motor to a receptacle in the fan housing. If this has come loose, the fan will not operate. Another cause could be the wiring was not done correctly. This usually only applies if it is a brand new installation. If after checking all of those without solving the issue, you probably need to replace the motor or entire fan.

The fan is working but the air is moving slower than normal: More often than not, this is because there is a build-up of dirt on the fan motor/blade or an obstruction in the ducting. Common obstructions include birds nest in the roof or wall caps where the air is being exhausted out of the home. Removing any blockage in your ducting or cleaning the inside of the fan according to the instructions in your owners manual will hopefully solve the issue.

The fan is operating louder than normal: First you will need to identify what type of noise it is making. If it sounds like it is operating normally just louder it might be because of some of the same issues described above in the air is moving slower than normal.

If it is more of a rattling sound it may be because the motor has come loose. Most exhaust fans have a housing with the motor attached to the housing with some type of mounting bracket. Over time the screw(s) holding the motor to the housing can work themselves loose. Tightening these might solve the problem.

Much in the same way, it could be that the screws or nails holding the fan to the joists have worked themselves loose or the ducting has disconnected. If you have access to the fan from above, this can be easily checked and corrected.

Other causes could be a weld has broken loose on the fan housing. Unfortunately, that cant be easily fixed and the whole fan will need to be replaced. If you hear more of a scraping sound it is probably the fan blade hitting the fan housing. This can happen if the blade was damaged during cleaning or if it has worked itself loose. Check to see if you can fit the blade back onto the motor shaft. If not, you might need to replace the blade, the motor or the entire fan depending on the extent of damage.

As always, Air King highly recommends consulting a professional for all maintenance issues. To learn more about other helpful tips visit the FAQ section at


  1. Humidity control knob no longer turns off fan in bathroom so exhaust fan runs continuously. It was working fine. Fan is in new apartment and wife and I are first residents. Two showers a day for three months. Any ideas? I will try turning off circuit breaker in order to do a hard restart and see the result.

  2. Thank you for your comment. A couple things could be what might be causing it. First, if it is a two speed fan (the model number would have a D in it), it will run continuously to meet an indoor air quality code. The low speed runs continuously then has a boost speed for when the humidity rises. A second issue could be the humidity sensor is set too low but it sounds as if you have already tried to adjust that. The last item might be that the sensor is damaged or not working properly. If that is the case, please contact our customer service department at 877-304-3785 and they will be happy to help you. If you could have the model number of the fan handy, that will be very helpful.