From 
Image 1 of 3
1. Pull the grille down and pinch the springs to release them from the housing. Then vacuum out the dust so you can find the model number.
Image 2 of 3
2. Unplug the motor and remove the plate that supports it. The plate will tip out of the housing after you release a tab or remove a retaining screw.
Image 3 of 3
3. Pull off the blower wheel and detach the motor by removing screws or nuts. Install the new motor and reattach the blower
wheel.
add comment: Ensure that all electrical connections have been turned off at the main electrical box and check to ensure there is no power. Luis