99 Suburban -a/c didn't work when I bought it. Finally got around to getting a compressor, evaporator, orice tube and flushed the system, installed everthing, vacummed it and went to add freon. A/c controller worked but I went to the front to add freon and a few minutes later when I looked inside since the clutch hadn't started cycling, the controller was burnt out and air only at floor ducts. Tried a new ac controller and it did the exact same thing. Everything works fine until you start adding freon then it burns out. So I took it to the dealer, told them exactly what was happeneing, they didn't find a shart but told me I had a leaky hose and needed new actuators for $2200. Had them replace the ac control head and same thing- everything works until freon goes in and I don't think they tried that. Taking it back next week but the guy was trying to insinuate it was the actuators. The first pressure switch autozone sold me for the back of the compressor wasn't right but the second one fit well. The dealer installed control head did last a few minutes longer.

Any sugesstions one what could cause that voltage spike to burn out the ac head or why such an expensive part isn't protected better?