AC Operation Front and Rear

[Max Funderburk]

'88 635CSi.....fellow big-coupers....can anyone tell me why the output from the rear AC console vents frostbites the back of my arm and elbow and the front AC just blows cool. The front gets worst as the temperatures rise into in the mid 80's (and higher) while the rear keeps nice and frosty.
Motor temps are normal-not excessive in the warmer summer temps (I have a 3rd party gauge) and it runs around 170 to 180 degrees....maybe a little higher if stuck in traffic.

Very strange having 2 levels (high and low) of output from one compressor?
Bewildered and hoping somebody has an answer..thanks in advance.

[Chris Wright]

Yes, classic sign of a low charge.

Here is a link to my diagram and explanation of why the back will blow cold and the front only cool that Da_Hose posted:
viewtopic.php?t=21047&highlight=

Try shutting off the rear (full warm) and see if the front blows colder?