I had to change a seized A/C compressor, I also changed the accumulator, and the orifice filter while I was at it. I got the compressor changed, changed the seals/o-rings, and did the same on the accumulator. I pulled a vacuum on the system and let it set for 45 min to see if it leaked. It did not. However when I pulled the hose off the low side fitting it started releasing the vacuum. The low side fitting is on the accumulator itself. I changed the schrader valve and that did not fix it, the leak still occured. I have added oil to the system, but not the refrigerant yet. This is my first time working on an A/C system and not sure what to do next.
1998 Crown Victoria
You can't pull the hose off when the system is under vacuum. The Schrader valve isn't designed to hold vacuum in. It's designed to hold positive pressure in. (unless you install it upside down).
The vacuum sucks the schrader valve open.
When your system is pressurized the valve won't leak.
