Replaced tandem compressors for Desert Aire unit. Removed entire charge, removed compressors, brazed in new compressors, wired everything back together, pressurized with nitrogen and found no leaks, vacuumed down to 500 micron. When we returned power to the unit the potential relay for 1 of the compressors blew up. Traced everything back and found a ground wire had broken off inside relay and shorted it out. Need to return with potential relay, add remaining charge (13lbs) and test system. Did not collect because repair isn’t complete.