I'm pretty sure the answer is yes. 1992 740, converted to 134a a long time ago. New receiver/dryer, variable orifice tube, and a junkyard seikio-seki compressor.

System evacuated, re oiled and charged with, according to the table in the faq, 950 grams of 134a. My math says I put in 930, but there were variables to how I had the can sitting on the scale when hooked up.

I did it when it was around 75 out. Vent temp got into the lower 40s, running pressure was around 30 psi. Compressor would rarely cycle. All seemed good.

The car has the two speed high/low fan mounted behind the radiator, high speed triggered by the radiator switch, low speed by the condensor high pressure switch.

Yesterday was in the mid 90's. It wasn't cooling that well. I also have a voltmeter mounted in the car and can tell based on the voltage drop whether the high or low fan has kicked on.

I was driving on the highway, 55-60 mph and had the following symptoms.

Compressor cycling on and off very fast, about 3 seconds on, 3 off. This could be felt with the gas pedal in a steady position and feeling the drag on the engine start and stop.

Low speed fan on all the time, even at highway speeds. When first charging it I verified its operation as normal at 0 mph.

This whole thing tells me that the pressures were high enough that the compressor was cycling on and off with the overpressure safety switch, the violet one I believe. It was also high enough never to trigger the low speed fan to kick off, even though I was moving at highway speeds. As a test I turned the ac off while driving and noticed the low speed fan turn off about 10 seconds afterwards.

My question - what to do? Even if my scale use wasn't perfect, I don't think I could have been off by more than 15 grams of charge. I did read in the faq that in hot weather its sometimes better to be undercharged so that pressures are closer to normal during operation. Is bleeding some off the way to go? Take it to a shop and have them pull it all out and put it right back in? If so, to what weight? 950, 925, 800?

Thanks, and sorry for the long post

Alex