I arrived for a single system heat pump cooling maintenance inspection. I began outside with the heat pump unit. Our client had recently replaced her filter and did not need it changed today. Outside I tested all the electrical components, everything tested within manufacture specifications except for the compressor start and run amps were above specifications. I proceeded into the attic and found the indoor unit to be cooling with more than a 20° drop and frost on the liquid line to the indoor unit. I then went back and check the unit Freon pressures and confirmed it was low on refrigerant. I showed all my finding to our client and we discussed her options. I did call Goodman, the manufacture, and they informed me the equipment was never registered and not under warranty. Our client elected to charge the unit up today and monitor the behavior of the equipment. She is aware that there is no warranty nor guarantee on the Freon used today. We also discussed how the lack of Freon is what