You must keep the exhaust fans clean to have function properly. Also, the dirt on it might have its health implications on the family. You must clean it regularly. Ensure that the fan is switched off. Use a dry cloth and wipe the frame first. The wings are also to be wiped using the dry cloth. Now, mix some detergent in water and use another cloth to soak it and wipe the frame as well as wings. Wipe it vigorously so that the dirt is removed. Use another dry cloth and wipe it cleanly. Do not switch on the exhaust fan unless you are sure that it is dried.