Unplug the dryer booster fan from the wall outlet, or turn off the circuit breaker supplying electricity to the booster fan.
Loosen the screw on the duct clamp holding the duct to the bottom, or inlet side, of the dryer booster fan. Some booster fans have screws that hold an access panel to the side of the fan housing. Remove the access panel to access the fan.
Reach inside the booster fan to wipe the blades with a soft cloth. Do not bend the fan blades, as this could damage the fan motor over time.
Replace the duct onto the bottom of the dryer booster fan, or replace the side panel on the fan housing. Tighten the screw on the duct clamp to secure the dryer duct to the booster fan.
Return the power to the dryer booster fan.