Performed a leak investigation for the basement system. This system had no standing pressure or a temperature split while it was running. This system has a major leak. Found the leak in the evaporator coil that is unrepairable. Will need to replace the 3.5 ton 17.5 wide B cabinet evaporator coil for a carrier unit (ADP brand coil). This job will take approximately 4-6 hour to complete. Will need someone home for that time frame. System takes up to 6-7lbs of 410A refrigerant. Will have to pressure test after repair, pull a vacuum down to 500 microns. Test the unit upon completion. This will complete the maintenance once system is back up and running. Paul Ash the service manager will follow up with a price and time frame once he locates the coil from pierce phelps the carrier dealer. Replaced both Merv 11 16x25x5 air filters for both systems during this visit today.