Theory... anyone confirm ? - PeachParts Mercedes-Benz Forum

Amuso · #1 12-07-2007, 09:37 AM

Had some sparetime here at work and read through a lot of the DIY articles. Great job to everyone involved. Very interesting and good reading.

All this got some of the braincells to start working and I started wondering if some problems I have might be connected.

I've noticed that the engine will idle at 1000+ RPM when warm, but just sometimes. When cold I have never seen that high idle. Starts up right at 750-800RPMs always.

The heater fan (inside cars coupe) will just work on setting 3, but sometimes on setting 2 as well. The glovebox light will work also when the fan works at setting 2. The glovebox light doesn't usually work. I checked the switch.

This made me think that maybe a fuse has a bad connection, but also that maybe the OVP is acting up so that when the fuse is ok and glovebox light and heater fan works, the car idles high. Maybe this fuse feeds all these circuits in some way. Will be interesting to troubleshoot for more details this weekend. But I think I might be on to something.

I had a bunch of electrical problems with my W124 300E, so I am not unfamiliar with those

I guess it will be a complete fusebox replacement with ATE-fuses instead on this one as well.

What do you guys think? Am I just imagining things or perhaps onto a few gremlins?

Amuso · #2 12-09-2007, 06:04 PM

Did not find any obvious correlation between the fuses and the blower working on 2 and not just 3.

Reading up a bit here I guess I will check a bit more around the control unit for the blower fan, and the blower fan itself. Is the control unit attached to the blower motor, or placed somewhere else?

Though I got my fog lights back because one fuse had a bad connection. Then I could also turn off the headlights and just have parking lights on. Takes time to go through all this extra wiring because of the ambulance stuff fitted to the car.

ejsharp · #3 12-10-2007, 12:16 AM

I would clean contact points of all related fuses, then test. If problem persists, I would open dash and check/trace wires to fan switch etc.

david s poole · #4 12-10-2007, 11:02 AM

i would use a good ohm meter on the 200ohm scale and check[with ignition off]the impedance between centre of the battery ground and good clean ground on engine.

Amuso · #5 12-12-2007, 03:33 PM

Ground is good. 0.2 ohms. Cable looks rather new.

Is there a control module for the blower? Anyone know the location of it?