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92 BMW 535i 3.5L; Seiko Seiki ss-148pb5 compressor; system completely empty within 24 hr.s AND 15-20 minute A/C functional drive. no bubbles after partial (3 of 4 cans) r-134 fillup. get a very weak, intermittent response from tif type leak detector around compressor pulley. couldn't find an evap drainage tube but ran leak detector near every undercarriage orifice I could find and got no response. left gauges connected overnite and surprise-surprise gauge pressures showing ambient garage temperature. Should I condemn front shaft seal, compressor or look for something else???
Get a spraybottle and fill with soapy water (dawn dish soap). Pressurize system with air or nitrogen and spray all connecting points and charge ports as well as condenser. That fast of a leak should show up pretty quick
Sorry, I conflated 2 thoughts into 1 bad sentence: To be clear- I found no bubbles after filling system with air and sprayed all connections with soapy water. Then I evacuated and filled the system with 3 cans (system capacity is 56oz.) of r-134 and got a very mild, intermittent response from compressor front seal area with electronic detector. The car has now sat for 36 hours and the pressure gauges still match ambient temperature. Since the system only seems to go empty after considerable running time, I'm thinking the only component that can exhibit that kind of intermittent leak is the compressor front seal. What do you guys think??
That is a possibility same as the air compressor seals if its a split case design. If you have a UV leak test kit it will show up. Did you spray all of the condenser or just fittings?
If you can't find the condenser drain, did you try putting your leak detector in the center air vents? Sometimes that will indicate when you have an evaporator leak.
Also, have you checked your service port valves? A leak that doesn't show with gauges can often be a bad shraeder valve.
If he's looking for a leak, what's he going to do with a pressure/temp chart?
I have seen compressor case leaks that passed a vacuum leak test but would leak under pressure. The compressor shaft seal can do the same thing and leak worse when spinning. The other common place for leaks that seem to happen more when running is the condenser.
He was mentioning that after it sat for 36 hours that pressures matched ambient temp and with it being static pressure that is about right. Though my fat thumb clicked wrong image lol here is the right one for static pressure
Those charts are a rough guess, at best. During charging, I've seen the proper static pressures in the system with as little as 1/4-1/3 of the requisite charge. When you add the rest it doesn't change the static pressure very much. So, you can be as much as 1/2-3/4 low on charge and the static pressure will look normal. It just tells you there's enough for the compressor to turn on, at least for a brief time.
I think he's just comparing that to a day of driving it where all the refrigerant leaked out in a day.
