Do you know how to repair the bathroom exhaust fan if it is noisy or not removing the moist air out as well as it use to? The fix might be a simple cleaning and an adjustment of the fan or it might need the motor replaced. If the bathroom exhaust is not removing the moist air then you should get it fixed before you have mould problems.
The first thing to do to repair a bathroom exhaust fan is to remove the vent cover by pulling it down and squeezing the spring clips together to remove them out of the slots. If the wall switch is off there should be no power at the fan. Unplug the fan and remove the screw to remove the fan motor from the ceiling housing. Vacuum the fan and the housing and check that the fan turns freely. If it is rubbing you can pull it up slightly. Be careful not to pull it up too much or it will rub inside the housing.


Plug in the fan and see if the motor is noisy. If so try putting some oil on the bushings and plug it in again, be careful of your fingers when you plug in the fan. If it is no longer noisy then remount it in the housing and plug it in and switch it on. A quiet fan quiet is fixed so you can replace the cover, but if it is still noisy it could be that the  fan is rubbing on the housing or it could be from the duct in the attic being too small or not supported properly and vibrating.
If you have not been able to repair the bathroom exhaust fan have determined that the fan needs to be repaired then you can replace just the fan and motor without replacing the exhaust fan housing in the ceiling. Get the make and model number from the fan and take the fan into the hardware store. Check to see if can still get the same make and model of exhaust fan, if not open some boxes and compare the fan. You are trying to find a fan that that will fit into your existing housing. You might have to use a self tapping screw to screw the new fan into your housing in the ceiling. The new fan housing that you have purchased can be discarded.


Now that you know how to repair the bathroom exhaust fan you can do it yourself or you can call your local  handyman to do it for you. While you are working on the fan it is a good idea to check the vent pipe in the attic. You would be surprised how many houses I have seen where the moist air just vents into the attic and is not vented to the outside. In fact I have seen fans where the vent pipe has come off the fan housing and the moist air is venting under the insulation. Knowing how to repair the bathroom exhaust fan is only half the battle. The vent pipe in the attic needs to be supported so that there are no vibration noises, there should be no low spots where water can puddle in the pipe and the pipe should slope up to the roof or exit point on the gable end wall. An insulation sock should also be on the pipe so that you don’t get condensation freezing on the outside of the pipe in the cold weather.