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c200 classic -98 with 280000km

The cooling fluid is on as soon as I start the engine, the level is fine and no air is trapped in the system. Also, the electric fan does not kick in so the car overheats if im stuck in traffic etc. Before the fan was always on when the car was, and later it was on even if I turned off the car - so I had to unplug it to avoid draining the battery.

I checked the cooling fluid sensor and window washer sensor got these values, are they correct?

Cooling fluid sensor: 110 ohms
WW fluid sensor: 173 ohms

Did check the electric fan control unit that is located by the driver side wheel well and when I opened it components were blown, circuit was damaged and everything was corroded as hell. So I bought a new control unit, replaced it hoping it would solve both the cooling fluid lamp and the fan problem, but nothing.. Where do I go from here?
 

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1998 c230 170K
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Hey thanks for your help and pm B!

Did check those links and will check the corresponding tips like fuses relays etc.

But! The strangest thing happened. The cooling level light came off today! Mind you, it has never ever been off for the past 2 years, but now that I changed the electric fan control unit the light actually goes off and stays that way 90% of the time. It is usually on when I turn on the car, but goes out in 1-3 mins - or it is off when I start the car, comes on in a random amount of time and goes out again. I have not found any connection between when the light goes off and the circumstance (ie, I hit a bump, steer left/right etc), it seems totally random.

So I have partially fixed the problem, but there is still something there..

Also, did not check if the fan came on because the car did not get that hot. But I read now that if you turn the AC on full blast, the fan should kick in within a minute or two? Will try that tomorrow and write back with my progress!

thanks again
 

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The SAM seamed fine to my visual inspection

Checked out the fuse/relay box on driver side next to the windshield. All fuses were ok and the relays seamed fine, no sign of oxidation moist etc. The only problem I found was the green relay, when I shake on it it sounds like something is loose inside and looking at the pics below it looks like moist/dirt/oxidation.

Also, that green relay is supposed to control the fan HI setting? Because, now the coolant level light is almost always off, but every time I turn on AC full blast, the light illuminates within 30 seconds and the fan does not kick in. Safe to say that this relay is causing it? Can I test the relay with a multimeter?

Its a SIEMENS with nr 002 542 03 19

http://public.openmindedprojects.com/bil/IMG_1062.JPG
http://public.openmindedprojects.com/bil/IMG_1063.JPG
http://public.openmindedprojects.com/bil/IMG_1064.JPG
 

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Changed the green relay today, was about $10 and the new one also sounds like something is loose inside when you shake it - so I guess it is normal.

Too bad it didn't resolve my problem, everything remains the same. But I do notice something - when the car is below 80 degrees C, the coolant light stays off, unless I turn on the AC - then it comes on and goes of in ~1 min after I turn off the AC. But when the car gets a bit warmer 82-85 C, the light comes on and goes off, randomly it seems..

Is there a way to check that the fan is working, connecting it to a power source?

Also, I had the ignition on but the car off and I disconnected the temp sensor on the engine (right in front of the fan) but nothing happened, is the fan supposed to turn on in this situation? You could hear the water pump and the air condition fans turning but that was it..
 

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It appears you replaced the relay for the "pane washer system" according to the chart on the russian website. It shows a listing for at least 2 for fan stage (s) one and two.
Yes you could apply voltage to the fan.
Êàòàëîã B
 

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Yes you are quite right, it was that one I replaced *doohhhh*

Looking at my pic, those three nearest the right bottom corner should match 0015428219 , 0025420119 , 0015429619 according to the russian site. Will check and report back. Can I test their function, think they can be opened just clips holding them closed.. maybe open and check inside?

http://public.openmindedprojects.com/bil/IMG_1066.JPG

The empty slot to the right should be empty because I don't have some equipment or somebody forgot to replace it?
 

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May be for an aftermarket alarm or the phone sys. No its not been forgotton.
Did you verify the fan operation?
I believe the fan stage (s) are blue and green, not the ones you have posted at least on mine. What was the ECT readings? B
 
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