To clean a kitchen exhaust fan, one needs rubber gloves, ammonia, a scrub brush, paper towels, boiling water, baking soda or trisodium phosphate cleaner, a breathing mask, and a bucket. These products are used to clean both the filter and the fan mechanism of the appliance.
The first step in cleaning the exhaust fan is removing the filters and placing them in a sink filled with boiling water. If the filters need further cleaning, remove the mesh part from the frame and soak it in a mix of a half cup of ammonia and one gallon of water for an hour. Remove the filters from the mixture and scrub them while using rubber gloves and a breathing mask. Let filters dry before returning them to the fan.
Use either trisodium phosphate cleaner or a mixture of one quart water, two tablespoons baking soda, and a quarter cup of ammonia to scrub the parts of the fan. Make sure to dry the parts after each one of them are cleaned. It may be necessary to repeat this process multiple times depending on when the exhaust fan was last cleaned. Kitchen exhaust fans should be cleaned at least once a year, and the filters should be removed and cleaned about every three months.