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Will not hold vacuum

CmonRef on Sun June 30, 2013 3:07 PM User is offlineView users profile

Year: 1980
Make: Porsche
Model: 911SC
Engine Size: 3L
Refrigerant Type: 134a
Ambient Temp: 90

Aftermarket system installed in 2005 ran well until mid-2011 when the swivel discharge fitting that held the 134 port and the pressure switch sprang a bad leak and dumped the charge. I was going to remove the engine for extended work, so I just sealed up the system and left it for 2 years.

To put the system back into operation, I replaced the drier and had to replace two lines because of corroded fittings. Replaced the 25-year-old compressor with a new one and modified the suction and discharge hoses to suit. Max vacuum was 20 inches which went to 0 a minute after stopping the pump. Replaced 8 of the 16 o-rings (six are REALLY hard to get to, so they have not been replaced - yet.) Also replace the three hoses on my vacuum manifold set since I could not find R-12-style seals. Still 20 inches.

With the vacuum pump running and 20 inches on the gauge, when I close the discharge valve, the vacuum goes to 22 inches, then returns to 20 inches in about a minute. Starting with 20 inches and both valves open, closing the suction valve produces a steady 13 inches. Starting with 20 inches and both valves open, closing BOTH valves and letting the pump run produces 0 inches in about 2 minutes.

Is there anything I can deduce about the location of the vacuum leak?

Don't have the capability to install a charge to try that method of finding the leak. If I don't happen upon the leak, it will be off to the auto AE shop ...

Brian

iceman2555 on Sun June 30, 2013 7:21 PM User is offlineView users profile

Use a small can of refrigerant....does not take much to test a system. You will have a small amount of waste. Have you checked your manifold/hoses for leaks...could be there and not in the vehicle.
Good luck

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