My A/C system in a 94 Crown Vic was completely empty of refrigerant. I replaced the accumulator, o-tube, and a bunch of o-rings. When I put the vacuum pump on it and let it run for 50 mins or so I can only get the vacuum down to -20psi. I shut it off and it holds there (going on 3 hours now with no change)
If there was a leak in the system wouldn't the vacuum give up over time and eventually equalize? Is this just as low as I'm going to get it?
You've got a small leak somewhere between the pump and the line fittings on the car. Air is coming in and causing the lack of full vacuum. When you close off the car's system, it holds at whatever it has been pumped down to. Which is good. You'll need to find the leak. Had it happen to me and it was a bad o-ring on the adapter that goes from the gauge lines to the car's fitting.
Garrett Fulton
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