PeachParts Mercedes-Benz Forum - View Single Post - Resurrecting a dead A/C

Diseasel300 · #17 04-01-2017, 04:58 PM

Nothing quite prepares you for the stupidity of things the PO did. Apparently the compressor was changed at some point in the 90s, as it has a 90s identification tag and shows it is suitable for HFC-134a refrigerant. No idea what refrigerant the system was running, it does not have conversion caps on the Schraeder ports, and the original 1986 R12 expansion valve is still installed. I'm assuming they were running R12.

Unfortunately a butcher got a hold of it and I'm at somewhat of a loss as to what they were trying to do. Clearly the system was failing to work due to leaks at the O-rings (rock hard, compressed, brittle, etc). Someone decided that the best way to deal with this was to remove the RPM sensor (completely removed, wiring harness included!) and simply attach a hot wire to the remaining clutch terminal. Wire was still present, but no longer connected to anything.

You can guess the result. Compressor had a very unhappy end. Seized solid, and the swash-plate inside is heavily galled and shows signs of melted metal. The filter-drier seems to have done its job, everything past it was clean, however the filter-drier itself appears to be from the factory as well. Big no-no not to change it when changing the compressor!

Spent most of today taking lines apart, replacing O-rings, and flushing the system. The condenser was a horror show. Evaporator was clean, but full of oil. I mean FULL of oil. No way that could have happened without the pressure switches being bypassed.

Regarding the expansion valve: Take whatever your expectations of how bad that job is going to be and multiply them by 1000. The fittings had clearly never been off of mine before, and what an epic pain in the ass. I'm debating saying it was worse than the injection-pump fiasco from last year. Drain line is rotted out and will be replaced with tubing. What a stupid design....

Tomorrow will get the compressor mounted, Filter/drier installed, pressure-test, pull vacuum, and hopefully charge with refrigerant. Stay tuned...