In most cases this job won’t put you in contact with any live wires, but powering off the fan at the circuit box will protect you in case of faulty wiring or freak accidents. If you cannot access the circuit breaker, turning off the local switch that powers the fan is usually enough to protect you. If you need a ladder to access the fan, make sure the ladder is stable before you climb.
On combination fan + light fixtures, wait for the bulb to cool, then unscrew the bulb to get access to a screw or nut holding the whole motor assembly in place. Remove this, then skip ahead to the troubleshooting instructions. [4] X Research source
If you can’t access this wire yet on your model, then removing the fan could put you in contact with your wall wiring. In this case it is especially important that the power is off at the circuit box, not just the bathroom switch.
If you have a high-output fan, you might just see one large plastic unit held in place by several screws. Unscrew these, then remove the entire unit from the housing. If there’s no obvious way to access the motor inside, look for a model number stamped on the unit and order a replacement for the whole piece. [8] X Research source
If none of the info above matches your fan’s description, you might have a less common model. Look for additional clips, screws, or other fasteners holding the motor in place. Some motor assemblies need to be rotated by hand before you can pull them out. [10] X Research source
Even if this doesn’t fix the problem, it’s useful to know. If the fan blades themselves are bent or broken, you’ll need to replace this part as well as the motor. If the assembly has an ordinary power cable attached to it, you can plug it into a wall socket to test it more thoroughly.
If the previous installation attached the appliance using nails, replace these with screws. Nails can easily vibrate loose and add to the noise. [14] X Research source If your fan has an ordinary power cable attached, you can test whether the buzzing noise is gone by plugging it into a wall outlet. Otherwise, you can reinstall it in your ceiling as described in the next section, then turn on the power. If the buzz is still there, turn off the power at the circuit breaker before you remove the fan again.
Most models are very straightforward, with just one motor and blower assembly sitting alone inside the housing. The motor is connected to the shaft that spins the fan blower, with wires coming out the side or back. If you don’t see a product code, try pulling the blower off the shaft to reveal more of the motor. If the metal or plastic housing around the unit is worn down, you might want to replace the whole thing. In this case, look for product information stamped onto the metal plate that the motor sits on, or on the plastic cover around the fan/motor assembly. [16] X Research source
CFM (cubic feet per minute) is a measure of the fan’s air flow. [19] X Expert Source Mitchell NewmanConstruction & Interior Design Specialist Expert Interview. 7 June 2019. Bathrooms need a fan with at least 50 CFM or 1 CFM per square foot of floor space, whichever is bigger. Outside of the US, the air flow is more likely measured in l/s, liters per second. Sones are a measure of the fan’s noise level. If you want a quiet fan, look for a replacement rated 1. 0 sones or less (about the volume of a fridge).
If the motor has an ordinary power cable attached, plug it into a wall outlet to check that it’s working. If the blower is wobbly or you hear rattling or buzzing, unplug it and double-check that all pieces and screws fit tightly together.
Once you’ve finished the installation, turn the power back on to check whether the fan is running smoothly.
