Upon arrival, I discovered that in a call for heating the outdoor unit would begin cooling. I checked my O wire outside, and I found voltage on it when there shouldn’t be. This indicated that there is a short in the wiring. I checked all of the spare wires to common with all of the wires unhooked from the defrost board. They all had voltage on them with them not being used at the airhandler. This narrowed my search to the wire going to the outdoor unit. I could not locate an obvious short, and I even checked the conduit outside that had water in it. I completely removed the conduit and checked again. I still found that all of the spare wires are shorted. I wired the defrost board back up and it failed. I unhooked O to allow it to heat, and I jumped power from Y to the contactor because it quit passing power. I cycled the unit to ensure it would shut off when satisfied. System is temporarily heating with defrost board bypassed and O unhooked. Customer approved rework for warranty defros
