Radiator Fan Problem

[AntM]

Hi there,

The radiator fan on my W209 CLK55 is running full speed all the time. It sounds like a 747 getting ready to take off!
I have heard that it could be caused by a faulty control unit?
Does anyone have any experience of this?

I'm not completely handless and would rather not pay the MB rates for the repair, especially if its a plug'n'play, rather than plug'n'pray unit.

Thanks for any assistance,

Tony

 

[fudge1200]

Mine runs all the Time when the air con is on, very noisy W220.
Have you tried it with A/C off.

 

[renault12ts]

Mine has never run...even with aircon on. Do you have electronic climate control??

 

[gerrypmckenna]

sounds like a faulty overheat stat these can be replaced quite cheaply

 

[fudge1200]

sounds like a faulty overheat stat these can be replaced quite cheaply

Where is this located, are you talking Cooling system Thermostat.

 

[gerrypmckenna]

yes cooling system thermostat they are sometimes faulty had this problem on my
last mb cost £9.95 from euro car parts

 

[gerrypmckenna]

locate where the wires from fan are conected you should find a small conection plug at the front of engine this is conected to asmall sensor held in place by a retaining clip remove retaining clip and sensor should come out there is a sealing ring you need to retain and fit to new one make sure engine is cold and ignition is switched off

 

[fudge1200]

locate where the wires from fan are conected you should find a small conection plug at the front of engine this is conected to asmall sensor held in place by a retaining clip remove retaining clip and sensor should come out there is a sealing ring you need to retain and fit to new one make sure engine is cold and ignition is switched off

But that is the Temprature Sensor, not the Thermostat.

 

[gerrypmckenna]

It sits on top of the thermostat

 

[fudge1200]

So if that is faulty, would that bring the fan on when the A/C is on, or does the Fan always run when A/C is on.

 

[AntM]

It doesnt seem to have anything to do with the A/C. I've tried it with it on and off and there is no difference.

Was in the garage today and they want to stick it on the computer. They reckon that it might be the Speed Control Unit for the fan, but it looks like that is part of the fan housing and will cost £400!!

Have removed the fuse for now and am keeping an eye on the temperature gauge! What a bummer!!

 

[AndyPCD]

Does the fan come on as soon as you turn on the ignition.

The best thing to do is get the fault codes read as this will give you a better insight to what is going on.

I have excatly the same fault on a customers car and they have already had the temp switch and fan replaced and the fault is still there

The fan was replaced with a non genuine one so could still be the fan.

Also do you get any warnings on the dash like coolant visit workshop

 

[fudge1200]

That is exactly what the guy told me at Mercedes, I thought it may have been the Temp sender bringing the fan on early, but he said I could spend a fortune trying to second guess what it could be, his advice was to put it on the computer see what it brought up. He did tell me that if it was the fan, the viscous coupling could be bought for about £200 Everybody else says the fan and motor all come as one unit £550.

 

[AntM]

The fan comes on the minute the ignition is switched on.
The temperature sender was changed as that was showing a fault, but still no joy.
No alarms on the dash, I removed the fuse to stop the noise, and monitored the temperature myself, which gave a collant alarm.

Latest update is that the computer reckons that the fault is in the ECU - new one is £1200!!!!
Have sent the ECU to a repair shop and am sitting with my fingers crossed!

 

[HHHCLK55AMG]

The fan comes on the minute the ignition is switched on.
The temperature sender was changed as that was showing a fault, but still no joy.
No alarms on the dash, I removed the fuse to stop the noise, and monitored the temperature myself, which gave a collant alarm.

Latest update is that the computer reckons that the fault is in the ECU - new one is £1200!!!!
Have sent the ECU to a repair shop and am sitting with my fingers crossed!

Hi antM, had the same problem as you with my clk55, thing is they changed the ecu out with a new one and then it was fine for a week and then same problem.

did you manage to find out what the problem was? Im quite stuck now.

P.s Mycar was invovled in a front end collision , did you have this problem after any front end collision or anything?

If you can help out at all please email me on [email protected] (i have a 2003 clk5 amg as well)

 

[BlackC55]

The last one I did one it ended up being the fan control unit being faulty

 

[AntM]

Just got the repair completed. Work got in the way and delayed things for a couple of months!
There is a module available, which connects to the fan and prevents spikes being sent to the ECU, however MB said that the CLK55AMG did not need it.
I had the ECU was repaired and changed and I got the car back. It lasted 10 miles and then the fault returned.
The ECU was repaired again and lots of tests carried out to the car. We bought the fan module and tried again, and it appears that all is OK now!

Was not the cheapest repair, but it would have been much cheaper if MB had owned up and said that the fan module was required. I feel a strongly worded letter coming soon!

 

[robs996]

hi can any one help, ive just bought a 2003 clk 55 love the car after owning a clk 500 which was a great car but wanted abit sportier model, ive a problem with the cooling fan not working, on investigation after the warning "cooling fault" came on the dash it looks like the control module unit is more than likley duff on inspection its full of water and corroded so ineed of a new one £500 from merc "ouch" so looking for s/hand one, can anyone tell me if any other models use the same 850 watt unit/fan

 

[BlackC55]

I'm pretty sure they can be repaired. Search Cartronix waterlooville. They may be able to repair it.

 

[newhere2012]

The fan comes on the minute the ignition is switched on.
The temperature sender was changed as that was showing a fault, but still no joy.
No alarms on the dash, I removed the fuse to stop the noise, and monitored the temperature myself, which gave a collant alarm.

Latest update is that the computer reckons that the fault is in the ECU - new one is £1200!!!!
Have sent the ECU to a repair shop and am sitting with my fingers crossed!

did you manage to fix the problem in the end?