Exhaust fan cleaning, especially in the kitchen, should be regularly cleaned, either by yourself or a competent cleaning service. Your Kitchen Fan gets loaded with cooking grease. This kind of fan is usually ceiling or wall mounted and vented to the outside. Many such fans have a removable grease filter, which can be taken out and washed separately.
To clean a grease filter in the sink, soak the degreaser solution or steaming hot water with some automatic dishwasher detergent added,scrub with a brush, then rinse with a forceful spray of hot water.
Aluminum filters can go in the dishwasher, but put the filter in separately to wash, definitely not along with your dishes. After washing, shake out all the water you can and set aside to dry before reinstalling.
Most of the motor and fan units can also be unplugged and removed for cleaning. Wipe off all the grease you can with a dry paper towel, then carefully clean the fan blades with hot detergent solution, being careful not to get water inside the motor openings. The duct, grille, and surrounding area should also be washed while the motor unit is out. Use a white nylon backed scrub pad to loosen stubborn grease, but be careful not to scratch polished surfaces. A competent cleaning service will also know how to clean an exhaust fan very effectively.
Depending on the amount of cooking you do, consider cleaning your Exhaust fan at least once per month, both from a cleanliness standard and from a safety standard, in order to lessen a grease fire in your kitchen.