The unit should be thoroughly cleaned inside and out. Frequency of cleaning will depend on unit location and area conditions. Drains must be kept free of dirt and trash. Coils can be cleaned with a stiff brush, vacuum cleaner, or compressed air. Coil can be reached through access panels.
Check coil baffles for tight fit to prevent air from bypassing the coil.
Check panels for air leakage, particularly those sealing the fan and coil compartments.
Check for loose electrical connections, proper refrigerant charge, and refrigerant piping leaks.
Air filters may be installed on the condenser air inlet. Air filters should be replaced or cleaned on a regular basis depending on how dirty the operating environment is. Failure to clean air filters regularly will result in loss of unit performance and possible nuisance tripping of the high-pressure switch.
Source: Carrier (www.shareddocs.com)