Fix wiring short. Unit #3 had a low voltage wiring short on the high pressure switch wire caused by an evaporator coil bracing bracket coming loose and falling on the wire bundles beneath it. There was only one wire that was damaged. I cut out the bad part and used a crimper tool to fix and then used electrical tape to insulate from weather. Unit operating normal. Customer also had a blown control fuse on unit #2. I replaced the fuse and used every technique to find a short but I could not. The system cycled in heat, auxiliary heat and defrost mode normal. I charged additional diagnostic time for this unit.