The unit should be inspected once a year by a qualified service technician.
F-Supply Blower Wheel
Annually inspect supply air blower wheel for accumulated dirt or dust. Turn off power before attempting to remove access panel or to clean blower wheel.
Clean condenser coil annually with water and inspect monthly during the cooling season.
Clean the all-aluminum coil by spraying the coil steadily and uniformly from top to bottom. Do not exceed 900 psi or a 45 angle; nozzle must be at least 12 inches from the coil face. Take care not to fracture the braze between the fins and refrigerant tubes. Reduce pressure and work cautiously to prevent damage.
Clean condenser coil annually with detergent or commercial coil cleaner and inspect monthly during the cooling season.
Condenser coils are made of single and two formed slabs. On units with two slabs, dirt and debris may become trapped between the slabs. To clean between slabs, carefully separate coil slabs and wash them thoroughly. See figure 21. Flush coils with water following cleaning.
Note - Remove all screws and gaskets prior to cleaning procedure and replace upon completion.
Source: MaintainX (Community Member)