06-28-2024. Jake Kring. I arrived for a new customer system not keeping up. I spoke with the homeowner and found that some rooms are not keeping up. He showed me the location of the system and I checked the systems options. I found the system to be clean and the indoor evaporator coil to be extremely rusted. I also found the duct work to be undersized for this 3 ton system. I found the refrigerant charge to be low and the system had a high superheat and a low subcooling for this system that is controlled by a TXV. I explained the cost of the refrigerant and the leak search with a possible repair or replacement of the leaking component and we decided to add refrigerant to the system to see how low it is and have a better judgment on what steps to take next. This system holds 7 pounds of R22 and I added 28 OZ of R22 and set the subcooling to 12.3 deg per manufacture specifications. I then rechecked the system and found the temperature drop across the evaporator coil to rise indicating th