On my 1991 560SEL, I have a very frustrating leak in the a/c system. The car would hold pressure to 75psi on the high side. The rest gets leaked out. I replaced the condenser, low side hose and compressor.

I pulled a vac and it held, then I charged the system and used my sniffer to check for leaks. Nothing showed up at the condenser, lines or compressor, so I stuck it through the vents and up by the gas pedal where the expansion valve is supposed to be. Still no leak detected.

I've recently replaced the compressor and the condenser on this car in an effort to cure this problem.

Any thoughts as to where this leak could be would be gratefully appreciated. It's going to get hot in Texas over the next couple of months.

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With best regards

Al