I vacuumed the ac system yesterday for twenty minutes. The low pressure gauge got to 26 inHg and when I cut it off it didn't move from there for thirty minutes. So the system seems leak-free. But, the FSM says I need to pull a vacuum of 29.5 inHg. Any thoughts on this? The only thing I can think of is to try another vacuum pump.
Oscillation
sounds like a pump issue to me since it did hold. You may want to pressure test with nitrogen, I like to do that since the system operates in a pressure mode, and I like to know the compressor seal will work under pressure. Just don't go too high 60psi should be good enough.
on the vacuum pump if you just shut off the main valve will pump go lower? that is take the entire AC system out of the equation.
on the vacuum pump if you just shut off the main valve will pump go lower? that is take the entire AC system out of the equation.
Thanks Dave. My name is Perry, I think we've chatted on youtube. My weird username on here is because I created it when I was 16. The pressure test would be cool but I imagine I'd have to buy a bunch of stuff to set it up. 
When I closed off the valves to take the ac system out of the equation, there was no change on the gauge. Your input helps me feel I'm on the right track. Someone else told me the gauge might just be off. Maybe, but a pump issue seems more likely to me. I'm planning to try another pump next and will report back.
When I closed off the valves to take the ac system out of the equation, there was no change on the gauge. Your input helps me feel I'm on the right track. Someone else told me the gauge might just be off. Maybe, but a pump issue seems more likely to me. I'm planning to try another pump next and will report back.-
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