PeachParts Mercedes-Benz Forum - View Single Post - A/C Failure

franklyspeaking · #7 07-24-2002, 11:12 AM

Thanks everyone...this is a great help to my knowledge vacuum.

When I converted to 134A I followed the directions on the conversion kit that I bought. At the time the system was low on R12 and I did not have a source at any cost for R12 without taking it to a shop. I evacuated the system and added refrigerant and oil per the instructions (as I recall flushing was not mentioned - or was mentioned as optional). Since then the system has needed a can of 134A before each cooling season, and so there must be a slow leak (I think this is the third year). When I converted to Duracool I added no oil, again, following their instructions, as it is supposed to be compatible with 134A or R12 oils.

As mentioned, it seems to me that the compressor has been laboring even more so this summer. Also, when I check the low side pressure I would see greenish oil oozing out of the system. The amount of oil on the floor was suprising to me. I am wondering if this system had way too much oil in it, and since the compressor is the low point in the system, it was literally oil logged. I am no A/C expert, but from my industrial experience, I know that liquid levels in centrifugal compressors are fatal. The R4 looks to be some type of rotary or centrifugal compressor as opposed to the York, which appears to be a reciprocating unit.

A couple of other questions.....Performance Products recommends changing the expansion valve when changing the Compressor. Where is the expansion valve located in these systems? Flushing the system sounds difficult, because it would seem that you would have to pump or pressure the flush through the system? Removing the expansion valve would seem to be a help since it would be major restriction in the system (dividing line between the high and low side)? So you could flush from the expansion valve to compressor suction and from expansion valve to compressor discharge (or vice versa)? I noticed that JC Whitney sells a flusher for about $50 bucks that works with air pressure to force flush through A/C systems....am I going to need something like this? Could you use something like the pressure brake bleeder that I saw on this forum (a converted garden sprayer)?

I am in no rush to get this fixed. I work in an office all day that is way too cold, and I really haven't missed the A/C on the 20 minute drive home everyday (don't need it in the morning at all). So I am going to take my time and get my ducks in a row, before I tackle the project....even though I know that August and September are hot months in Alabama! Thanks for the help...you guys are a great bunch to be associated with.