Performed precision AC tune up. Checked operating refrigerant pressures. Found system low on refrigerant. Determined this was result of leak present inside evaporator coil upstairs. Tested power distribution system and corresponding starting components. Verified proper amp draw; optimal. Temperature differential across indoor coil below target due refrigerant loss. Purged primary drain line to ensure no obstructions. Used alkaline treatment to reduce bacterial growth within lines. Replaced existing media filter 20x25. Returning to replace Evap could under MFG. Will need to level condenser when we return to replace evaporator coil.