anyone?!:S please ive been at 4 mechanics so far and no one could solve it!!

its extremely annoying to have your car sounding like a jet engine all the time!

so please, i know you guys are one of the most experienced people in the world when it comes to mercedes, can anyone just help diagnose this problem? thanks guys..

 

So the car was diagnosed and some fault codes appeared but you do not know which ones? Do those codes still appear or did they go away when cleared or when the SAM and (likely) the fan control unit were replaced?

I would follow the wiring diagram from the fan backwards down to the AC control unit and see where the drive signal comes from. Did you try to disconnect the AC control unit?

Which ECU do you mean when you say "no fault codes from the ECU"?

 

Well first of all, thank you for repliying..

Secondly,we know what the codes stand for, and one was for the fan itself...so thats what made us change the fan..but it didn't work..so he changed that small rectangular metallic bit which im presuming is the fan control unit...

well we disconnected the ac control unit inside the vehicle, we started the car, but the fan still turned on, even though on the DAS it shows the the auxillary fan is being demanded at an output of 94% by the AC control unit..and i meant the ecu which is in the passenger side black box..is it possible that its a relay problem?

 

It sounds like there is a fault in the wiring or a relay that controls the fan and/or communication with the HVAC control module. When this happens, the ECU will often times put the fan into safe mode (always running) to avoid an overheat or melt down.

 

Oh ok, but we disconnected the Air con control module (the panel in the middle console inside the car) but that didnt solve anything...

Is it true that there are no relays for the fan exect the fan control unit which is located next to the radiator? If there is how can i find them? Is it possible my ECU is damaged? Thanks in advance:thumbsup:

 

If you disconnected the HVAC control module then you put the fan into safe-mode. The ECU thinks there is a fault in the system, so its turning the fan on. Can you check to see if the A/C compressor is cycling on/off as needed or is it always running? Is the A/C bringing the vent temp down to +/-40 degrees with exterior temp being 70-80?

 

Well, the hvac is cooling perfectly, and we disconnected the hvac control unit as a part of the diagnostics, the fan problem was already existent when we disconnected it.

I also just remebered, the fan was fine when we changed the fluid, but then we replaced the MAF, turned it on, the turned it off, put it on star..reset the faults..then turned the car again, when the fan problem emerged..

Could it be related to us replacing the MAF and reseting the codes on star? Thanks for your help!

 

Could it be related to us replacing the MAF and reseting the codes on star? Thanks for your help!

No, it shouldn't have anything to do with that. The fan should cycle on/off with your A/C compressor. That is why I asked if the compressor is running non-stop or what is going on. This could be related to your compressor or low refrigerant or the sensor that tells the fan to turn on/off based on R-134a pressure in the system.

 

Oh and one more thing, if I start he car on a cold start, the fan stays about 1 minute to turn of..hope that helps for something!

 

I noticed the electric fans coming on for short time even on winter morning. I think this is part of self-diagnose the car performs on each start.
I am not familiar with the CLK, but just weeks ago I fixed constantly running fan on older MB model. Turned out the temperature switch on top of the thermostat shorted and was sending constant signal of hot engine. That was separate circuit from temperature gauge.
I wonder where you live to find 4 mechanics in the row, that knows nothing about the 10 years old cars?

 

Well its not that the mechanics didnt know anything about the car, its just out the problem turned out to be totally unrelated to the symptoms..it was the MAF all along!

Turns out the mechanic replaced the MAF with a temporary replacement just in order to get the right Bosch MAF, but put a non-genuine aftermarket MAF in, which in turn put the ECU into "Safe Mode". He charged me 20$ for the diagnostic.

Well, personally i thought that might be the problem, but i didnt do anything about it because it was totally unrelated to what was happening with the fan. Good thing I have my old MAF in the boot, i reinstalled it until i have the time and money to go buy a new one. Well I guess the solution is not necessarily always the most complicated. So now my car is great! Just needs a new MAF along with getting something done with the Cat converters which were clogged due to thermal damage (Drove into a large concealed puddle-Hydrolocked the engine), and placing a new oil cover gasket sealant since its mildly leaking, plus the routine oil change and antifreeze flush.

Seriously, you guys have been great help and have given great advice! Cheers to you all!!:beerchugr:

 

Well its not that the mechanics didnt know anything about the car, its just out the problem turned out to be totally unrelated to the symptoms..it was the MAF all along!

Turns out the mechanic replaced the MAF with a temporary replacement just in order to get the right Bosch MAF, but put a non-genuine aftermarket MAF in, which in turn put the ECU into "Safe Mode". He charged me 20$ for the diagnostic.

Is it me, or there is a big conflict in those 2 statements?