Hello: I hooked up the hoses of my a/c recovery/recharge unit to my 1990 300SE and the gauges show zero pressure. So, unless there's something wrong with my a/c service unit, there's no gas in my car's a/c system. Is it common for it all to leak out? I have a bad pressure sensor switch that I'm going to replace along with the drier and the auxiliary fan switch. Would a bad pressure sensor switch normally allow ALL of the gas to leak out of the system?
Thank you.