Aux Fan 560 SL - PeachParts Mercedes-Benz Forum

BDBENZ · #1 07-22-2002, 03:08 PM

I am pleased to be a first time MB owner (560 SL) and new to the forum. Hello to everyone, I have enjoyed reading all of the posts and am learning something everyday. Now to my question...I have been checking out my aux fan, as it never comes on, and like mentioned in other posts on the subject, the temp gauge pushes 110 close to 115. The air works great, the MB dealer converted it last month to 134a with a new condenser, and dryer installed. With the temps over the weekend in the mid 90's and high humidity, the air is ice cold, but no fan. I jumped the engine temp sensor (green three prong) and the fan runs. If I jump the pressure switch at the dryer, the fan also runs, and in both cases it seems to be the same speed. The engine temp comes back down to 85 to 90 with the fan running and if you let it idle, fan running with the air on, it will hit 95 to 100 but no higher. Do I have a bad temp sensor or are both the temp and pressure switch bad? I would appreciate any help on the fix. Thanks....

Holson Adi · #2 07-22-2002, 04:07 PM

hhhmm interesting. I'm assuming that the switches are wired in parallel. Maybe you could try replacing the freon pressure sensor first as that is the one that triggers my fan. My engine's water temp rarely reaches 100C+

on a warm day (70F+) the aux fan would definitely come on after a while if the A/C is on and switches a few mins after the A/C is switched off.

One more thing to check is the aux. fan relay! It's called the ice cube relay or something due to its ice-cube shape. It's under a box on the driver's side wheel well (in the engine compartment obviously).

See if you could find that. Maybe it needs replacing!

BDBENZ · #3 07-22-2002, 08:09 PM

Thank you Holson for the advise, I will check out the aux fan relay, it could be the culprit. That would make since... This has been puzzling as to why it never runs. I have read all of the posts, but I would like to keep it a little cooler, closer to 85 to 90c. Besides, I want everything to work as designed. Thanks..