A/C Issue

[TJNE]

2003 Chevy Tahoe 5.3L. My wife started the Tahoe and she heard a pop and white smoke (R134a) come out from under the hood on the passenger side. When I checked under the hood I saw oily residue on the bottom side of the hood right above the high pressure schrader valve for the A/C unit. I run the engine for a few min then turned it off and could hear hissing from the same fitting. My question is it possible this valve "popped" off loud enough to hear from inside the vehicle with the engine running or should I look for another leak? Has anyone had the same problem? I looked in the fitting and saw a black rubber cap/diaphragm shape, I assume the schrader valve is under it?

[DmaxMaverick]

That's a pressure switch, and it sounds like it blew apart. Not common, but it happens. Identify if it's high or low (is the switch actually ON the high pressure line, or above it on the accumulator or low pressure line?). Under it is the schrader valve. The switch threads on/off. Replace the switch, recharge and you should be back in business. Don't let is set overnight with the blown switch, or the temp changes will cause it to draw moisture/air in. Remove the switch and the valve will seal, until you replace it. Because the system was never "open", you don't need a complete evac/service, just a recharge.

[TJNE]

Done. Replaced switch/valve, vacuumed and refilled. 42 Deg again. Thanks.