After a little truble shooting
 

John & Alkraut,

Thanks for the information.

I have two 580's side by side in the garage, a 87 blue SL and a 88 Red SL.
The RED 560's ACC is the "cool" problem. The BLUE 560's Acc works wonderfully. With both autos running and engines warm I found the following!!!

RED MBZ BLUE MBZ

Top and bottom hose of monovalve Top and bottom HHOT
cool to the touch

Large Ac hose and metal valve ambient Metal valve ICE COLD
cool to the touch!!

Does this mean that the RED compressor is NOT "engaged? How do I manually or electrictly engage the compressor?

Thanks again for the HELP
Jim E
560 squared

Jim, your info is a bit confusing as to which car had what symptoms. If you look at the AC compressor with the AC off you will see the metal part behind the spinning pulley is stationary. When the AC is put on high you should see the stationary part engage and it will spin with the pulley. May take a few seconds to cycle on. When on it should make the upper AC line ice cold. The top heater hose on the monovalve should be cool, not hot when the AC is on.