With regards to a 1992 300E...
I recently noticed that my A/C blows warm in stop-n-go but is cold at steady speed above 25 mph. Upon observation, the auxiliary fans are not coming on with the compressor (as I know they should). The last time I experienced this, the fuse was bad. This time around, the fuses seem to be okay. Is it my A/C relay, or R-12 level? This is confusing because the A/C is cold at speed and my fuses are okay. Any advise would be greatly appreciated.

Thanks in advance,
ARVY
1992 300E (152,000 mi.)
1984 190D 2.2 (163,000 mi.)

more than likely, a low refrigerant charge. it's not building enough pressure to trip the aux fan switch.

Try jumping the aux fan. Connect the two wire leads that come off of the top of the dryer. If that doesn't work, the fan may be shot. Also, as always, check your fuses.

Quick check for R12 level is to look at eye sight on top of drier/reciever...
..bubble stream/cloudy indicates low freon.
What happens is there is not enough freon to allow the condenser/high side to reach the cut-in pressure spec. to trip the aux fan on.
As posted, a jumper of the high pressure switch will test the aux fan electrical circuit..
Poor cooling condition at low rpm is indicator of low refrigerant..