92 400E AC (trouble solving problem)
 

The charge, pressures all at spec, the auxiliary fans are working properly, the interior sensor ok, climate control unit system ok.
When the engine is at idle, the ac blows warmer air. Ambient temperature 85F, system set at auto, max cool, when driving, the air temperature at center vents will average 42F (nice and cold). Then when at idle the temperature will climb to 58 to 60F in about 10 minutes. Upon initial start-up the air will cool down to approximately 60F at the center vents, and once driving the temperature will drop into the forties in about 5 minutes.
What do I check, puzzled, Thanks Tim?

Curious about that too.
 

Curious about that too. Same thing on my W124. Mine has R134, I know R12 is better on these cars. I will be switching back to R12 shortly.

My 400E ac has always used 134a, never a problem with not being cold enough, until last week. I've used the search enging, read a lot of about ac problems, but cannot find the answer. The belt, fans, engine temp, all have check out.

Could it be that at idle you are not producing as much vacuum as when driving, and that this drop in vacuum, is causing the recirc flaps to switch to the outside air, instead of cooling off cabin air?

I will check for a vacuum leak, and i'll see if recirculating switch has any affect cooling the air temperature at idle.

Today an MB tech suggested it might be the dryer, stating that was one of the weak ac links on my model, he thought mine is a one stage dryer and the replacement is a two stage dryer, any thoughts about the dryer solution?