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Old 08-31-2001, 10:14 PM
can-do can-do is offline
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Join Date: Jan 2001
Location: Tucson, Arizona
Posts: 758
Chiming in


I have done this conversion on my '80 300TD. Actually I did a complete replacement on major components because they were missing on my vehicle when I bought it. Stolen I suppose. I replaced the evaporator, lines, and the York compressor on mine from a salvage yard. I remembered to replace all the o-ring seals with the new R134 green ones as well as added a new filter/dryer before evacuating the system. If your system is totally dry of oil I would not follow the kit instructions of adding two cans of R134 before the oil/R134A mix. I would fill with the R134A then use the oil mix right after that. There's no lube or very little in the system and there is a possibility of locking up the compressor from lack of lube. The initial can just applies pressure to the switch to allow the compressor to actually start turning, but it's straight freon without lube. Try it my way and you'll end up with better success as well as a lubricated compressor. If you keep an eye on your sight glass it will tell you when the system has recieved enough freon, bubbles disappear, this is your full point, or 85% point. Shut off the freon flow and allow the system to run while still watching the sight glass. If bubbles reappear shortly there after add small amounts until it remains clear while running. You won't use the entire kit that you purchased, if so you probably over charged the system. Since June when I did mine it has been leak free and serving me well. When temps exceed 95 degrees it will not cool nearly as quick as R-12 did, but saved me money in the long run. These older Benz's just don't have the larger evaporator required to get the same effect that R-12 has on the system in hotter climates.

"Tell me and I will listen, Teach me and I will learn, Show me and I will accomplish, Involve me and I will succeed."
'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan

Last edited by can-do; 09-02-2001 at 12:27 AM.
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