I need some help understanding how the auxiliary fans on my 1992 400E work. From searching other threads on this site it sounds like they should come on at low speed @ 105 degrees and then full speed some time later. It also says they should come on when the AC is on. Unfortunately, they only come on at about 110 (if gauge is right) at full speed. They do not come on earlier at low speed and do not come on when the AC is running. Can someone please confirm the logic used to control the fans and what relays/fuses I should check. I did look at the Auxiliary fan resistor and the terminals look rusty, but otherwise ok. I did jumper past the resistor to see if the fans came on any earlier and they didn't.

Thanks!
Bob

Attached Thumbnails