I have been going through the forums and trying to do searches but it won't allow AC... hmmm and if I search on 134 convert I haven't found what I am looking for. - Anyway, my 87 300D was converted to 134A prior to me getting it. It was 90 yesterday with 55 percent relative humidity and it didn't cool very well on the way home, so I hooked up the guages to see what the pressures were. I am not an A/C person by any means so I need some insight. The high side was 310 and the low side was 30 with the engine running at about 2000 rpm. The sight glass looked white, so I am not sure if that means its low or not. I have no clue when it was converted to 134 and what was done. What I am trying to figure out are:

What should the high and low pressures be at that temperature/humidity/rpm.

I shut it off and let it cool down for an hour or so and the pressures evened out to about 100lbs on the high and low side. Does that sound about right? The engine was still pretty warm.

If I evacuate the system and flush it, should I change out the evaporator and anything else? How much 134A and oil should be added, and what type oil?

Also, another general question... I have a 30lb canister or 134A. If say the system needs 36 oz of 134A, how do I measure 36oz. I figure I can use a bathroom scale, but that isn't that accurate.

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