I arrived and replaced the thermostat. Once I replaced it, I powered the unit back on and the fuse popped again. I began evaluating the wiring and isolated it to the outdoor unit. I checked the contactor, pressure switch, and defrost board. At first, I thought the defrost board was bad. I began tracing every wire and isolating the low pressure switch and contactor. I determined that the pressure switch was the issue. I opened the top of the unit and found that the wire was burning. The wire was not exposed, but it was still causing a short. I adjusted the wire and wrapped it with electrical tape. I ohmed it and verified that it was still good. Customer still would like the thermostat and the system is cooling.
