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2012 ML350, 1999 ML320
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75 Posts
Discussion Starter #1
Originally fans would not start. Replaced fans (fried wiring), then replaced temperture sensor mounted in head. Got car to heat up and Auxilary fans kicked in a bit about the 100C mark.

Now Auxilary fans will not stop. I let car cool down fans still run. I removed fan relay next to fuse box (black relay) Fans then stop.

Ideas on how to remedy that one?

Thanks, Bryant
 

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'87--190E 2.3-16v(being rebuilt), '99--C230 Kompressor
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3,488 Posts
sounds like either they got wired in backwards or you temp sensor is bad...time it and see how long it takes to for the fans to shut off
 

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1993 190E 2.6, 1990 300SEL, 1992 300SE, 1992 400E, 1987 190E 2.6 murdered by my brother.
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1,291 Posts
It could be a bad fan relay- assuming that all the wiring is correct. Check the resistance of the CTS sensor when its cold. Should be very high Ohms.

Mine low speed fans would not turn on but my high speed fans would. I changed everything and it turned out to be the fan relay. $35 bucks from dealer
 

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'87--190E 2.3-16v(being rebuilt), '99--C230 Kompressor
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3,488 Posts
be lucky that at least yours are in working order....atleast once a month someone else's fans crap out on them
 

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2012 ML350, 1999 ML320
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75 Posts
Discussion Starter #5
I hear that 'Turnpike', LOL...

I found the schematics finally (nice download here) and will take some resistance readings, including the new parts to see what I can figure out. Just wanted to check in to see if I was missing something unique to this circuit.

Till then,

Bryant
 

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1993 190E 2.6, 1990 300SEL, 1992 300SE, 1992 400E, 1987 190E 2.6 murdered by my brother.
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1,291 Posts
Yeah the 1989 models are a little bit different than the 1990 ones with the EGR valve system. One thing is when you crank your engine your electric fans spins....my 1993 does not do that.
 

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Registered
2012 ML350, 1999 ML320
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75 Posts
Discussion Starter #7
Sensor in head responds to heat and resistance changes. Once the high temp is hit fans kick in. But when I let the car cool down to say 40C then start it fans come on and won't stop. I let it run for about 20min temp went up to 80C fans still running. Had to pull relay again. Wondering if the relay might be sticking so will get one online and we'll see.

Thanks all for inputting, will get it solved eventually.

Bryant
 
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