500E Fan Wiring?

[Uberwagon]

Hello all.

I am having a job to trace the fan wiring on my 500E. It has been running warm of late and I found this to be because a previously fitted resistor to lower the fan cutting in temp was failing.

I was told that removing the coolant sensor plug while the car is running should bring both fans in but it doesn't. If I short the 2 sensor wires together it turns on the fan infront of the Air Con Rad and this is what it does anyway in normal running.

The problem is that after a drive when going at lower speeds the water temp stays about 100°C, now when i'm parked after an hour or so when I turn the car back on the fan cuts in straight away and it takes a few minutes to turn off after getting back to 100°C again.

I'd like to run a switch which i'll mount in the dash (I have a space in my console so it can look factory) to run the fan on the left hand side of the engine when in traffic etc to keep the temps lower.

I cannot trace the wiring to the fan and the only way i'm going to find it is by removing the fan shroud, radiator and viscous fan.

I'd like to wire it in closer to the bulkhead if possible but just can't find the damn thing.

Any ideas guys? The websites which show how to do the resistor mod etc aren't any help as I still can't trace the wiring from them.

Regards.

Dave!

 

[grober]

speed v staging

I am a bit puzzled. Do you have 2 electric fans in front of the radiator and 1 viscous fan behind the radiator? According to jim Forgiones site http://pages.prodigy.net/jforgione/MB_CTS.html the 2 electric fans are wired from the same supply in parallel. In which case they should both come on at once. Have you tested the supply leads to the fans themselves for voltage when they operate. If the 2nd fan has a supply but is not turning then it is faulty. Thats assuming they both come on together and are not "staged"- one fan then if temp goes higher 2 fans on. The fine control seems to be achieved by switching fan speeds rather than "staging" according Jim F's site.

 

[Uberwagon]

It has 2 fans and 1 Voscous fan.

From how I understand it the fan infront of the AC Rad comes on at 98°C, the second fan comes on at 107°C and they both come on flatout at 115°C

I can't get to any of the feed wiring to the fans, unless I start pulling things off and if I can trace the wiring further down then that would be perfect.

Also, it doesn't operate like i've been told it should which just adds more confusion

Dave!