Mechanic hooked up wrong. He's running vacuum backwards through mode switch. Line operates heater core shut off valve. Is only active in Max A/C mode. Runs from passenger intake rail (one device of many on big 3/8" line), through mode switch, under console in hard plastic line, out driver's pontoon, to heater core shut off valve. Bill Robertson #5939 >--- In dmcnews@xxxxxxxxxxxxxxx, "aaron_t_graham" <aaron_t_graham@xxxx> wrote: > There's a lone vacuum line that comes into the engine from the side of > the engine compartment -- toward the back, on the left side. It's > quite lonely back in that part of the engine compartment, so it's easy > to see which line I'm talking about. > > If I have this line disconnected, everything still seems to work just > fine. Idle is good, acceleration is good, and all climate controls > work just like they should. My mechanic hooked it up to where he > thought it should be, and when he did that, lots of hissing noises > started coming from the A/C panel mode switch area. > > So it comes down to this: when that line is hooked up, everything > works okay and the A/C mode switch hisses. When that line isn't > hooked up, everything works okay and there is no hissing. > > Any ideas on this one? > > Aaron > #1506