Arrived on site to perform commercial AC diagnostic on heat pump condensing unit from 1997. Upon arrival client stated that system is operational today but there are times when he does not turn on at all or pump any cold air into the building which results in it becoming 80+ Degrees inside the show room. Proceeded to roof and found unit was operational. r22 condenser coil was replaced in 2019. Inspected evaporator coil and found that it was heavily covered in dust and debris due to no filtration inside of the unit and lack of maintenance. Measured amperage for compressor and found that it was extremely high indicating that the compressor is overworking and is at higher risk of going off on thermal overload on really hot days as well. Measured refrigerant pressures and found that they were in range although R22 was completely phased out January 1, 2020. Ultimately during the visit system was operational and cooling, system is past design life and any component at this point is at high r