Completed 7 system furnace repair and preventative maintenance check. Find Main house with 3 HP/AH system. -Upstairs system operating with in manufacturer spec. Filter still good. -Main system operating with in manufacturer spec. Filter still good. -Basement system 17 year old operating with stress compressor and high power usage, low charge and damage wire due to rats chewing on wire. Remove dead rat and repair wire for the customer. Suggest repair basement system. Give customer estimate. Find Guess house with 4 HP/AH system. -Upstairs new system operating normally within manufacturer spec. Filter still good. -Upstairs system for bedroom 17 years old molded and dirty. Find system evaporator coil badly rusted. Missing inline water protection for the system in the attic. Motor and compressor in poor conditions due to age and ware on parts. Low on charge. Give customer estimate to repair system, but suggest to upgrade system due to age.