Help....is is leaking and I cant find it! Hi, I have a 83 300SD which has suddenly developed a leak. I have pulled the system down to 20" of merc and it will equalize back to 0 in about 2 minutes. I've checked all fittings and hoses with a Robinair freon leak detector, and still can't find the leak. Any suggestions? Al Wong 83 300SD

2 minutes sounds pretty quick, if not an o-ring and there is no obvious leak, did you also go up under the dash above the gas pedal at the expansion valve? Also, the compressor front seal could be leaking, in which case you need to hold the leak tester just below the compressor because the freon ofter disspates beofre the meter can pick it up.

Personal experience: I seldom use my leak detector any more. First I look for the ref. oil on the entire system. If there is a major leak, the oil is there also. I always charge the AC system with dye, that way the small slow leaks are seen with a UV lamp.

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