An air conditioning service should include the following actions:
Inspect the fan for damage.
Replace all air filters.
Check the thermostat to make sure it is functioning properly.
Verify wire connections are secure.
Check levels of refrigerant.
Inspect ducts for leaks, cracks, mold or dirt accumulation.
Examine condensate drain to check for obstructions.
Clean evaporator coils.
Lubricate moving parts to reduce friction.