I arrived for a new customer no cool call. I spoke with the homeowner and found that the system is running and cool it it is having a hard time keeping up and it’s struggling. I inspected the system and found everything to be running. I inspected the system in the attic and found the evaporator coil and blower wheel to be clean. The evaporator coil is extremely rusted. I inspected the condenser and found the system to be running low on R22. This system holds 15 pounds of refrigerant. I made this aware to the homeowner and explained our no warranty policy on refrigerant. We decided to not look for the leak but add refrigerant to the system. I added 3 pounds to the system and set the system superheat at 10deg. I recommend to start planning on replacing the system vs keep adding refrigerant to the system. This system is running and cooling at this time.