560SEL Auxiliary Fan diag & questions
 

I have a 1991 560SEL, recently I started to notice the A.C not blowing as cool as it should. In the past 2 weeks when temps were well over 90 deg, the A.C would cool but not as much as I would like it to. I did notice that the Auxiliary fans did not come on during this extensive heat whether in traffic or while driving. During stop and go traffic the A.C is cool to warm and best and the engine temp rises but does not overheat. I checked the fuse to the fan and it is good. Last summer I did not have this issue..

At what temps are the low and high speed fans suppose to come on?

How often do these units fail on this car?

I have yet to check my fan temp sensors & relays. Can someone provide a link to the wiring diagram for this system?

Would like some straight forward diag info so I can fix this issue. Searching the forum got me confused. Thanks

The fans come on based on AC pressure, not temp (at least for low speed). They'll kick onto high at 110*C coolant temp.

-J

Electrical diagrams 86 and on....
http://www.startekinfo.com/StarTek/outside/12253/program/ETM/126from86.pdf

Climate Control Electrical Diagrams 86 and on...
http://www.startekinfo.com/StarTek/outside/12253/program/ETM/ACCfrom86.pdf