I have completely overhauled my 93 gallant ac system as of now, the problem i am having is that prior to replacing the evaporator coil and expansion valve , the expansion valve stuck in the open position which cause the low pressure side to over pressure which in turn caused the overpressure popoff valve on the back of the ac compressor to trip. does anyone know where I can order one or does anyone have an old ac compressor laying around that they would be willing to sell me the popoff vave ? any help would be appreciated.