Performed diagnostic on 4yr old upstairs unit, upon arrival customer stated unit stopped working yesterday and tstst went blank, inspected tstst, found no voltage, went to attic inspected system, found no low voltage to transformer, explained to customer there is a low voltage short, inspected all low voltage wires, found nothing at air handler, inspected outdoor unit, found pressure switch wires touching copper line, recommend fixing wires and replace transformer to get unit up and running, customer approved, fixed wires, and secured wires, installed new transformer with a fuse, unit started up, spoke with customer about home care, customer agreed and wanted to perform visit today, checked both system in heat mode, checked heat strips, capacitor, contactor, blower wheels, downstairs blower slightly impacted, recommend pulling and cleaning, flushed both drain lines and used endure, recommend adding vent to both drain lines, recommend added wet switches to prevent water damage for both