HVAC Maintenance Guidelines
It is recommended that maintenance of HVAC equipment be carried out as follows:
Filters: The function of filters is to maintain the quality of indoor air and ensure protection of the components from dirt that affects their performance efficiency. The filters enclosed in cardboard with holes should be avoided since these decrease their operative area, and increase the drop in pressure. Performance of the pleated fiber filters is better since filtration efficiency is enhanced by fabric, the effective area is increased by pleats, the pressure drop is reduced, and the life of filters is increased. Filters should be changed based on pressure drop across the filter, visual inspection, or calendar scheduling.
Evaporator and Condenser Coils: Dirt on evaporator coils reduces air flow in the system. The heat transfer efficiency of coils is reduced by dirt, thereby decreasing the cooling capacity. The evaporator coil will remain clean by good filtration, and should therefore be inspected at minimum on a yearly basis to confirm the usefulness of the filters. The exposure of condenser coil to unfiltered outside air makes it more vulnerable to degradation by dirt, and should therefore be cleaned periodically.
Compressor: In an overcharged system, surplus refrigerant stores in the condenser, and makes the compressor work harder. In an undercharged system, refrigerant is reduced in the evaporator and cooling capacity is decreased. This is indicated by frosting on the entrance of evaporator and a warm suction line. Undercharging occurs due to some leakage in the system. A compressor that is not producing the desired cooling effect may require replacement when the discharge pressure is reduced, or the suction pressure is increased, beyond the limits recommended by the manufacturer.
Fan, Bearings and Belts: Impellor blades can be filled with dirt that can be minimized by good filtration. Indications of bearing malfunction are unnecessary sound, excessive vibration, or heated bearings. Fans should be oiled in accordance with the recommendations of the manufacturer. Suitable tension should be maintained in the belts, and application of grease should be proper.