C200 Fan starts automatically while parked! HELP REQUIRED

[MercFault]

Hi Everyone,

I am writing to ask about a problem I have been facing with my Mercedes C200, 2015 Model.

When the car is parked with ignition switched off (even if parked for many hours at a stretch), the cooling fan turns on and off intermittently until the battery dies.

While the fan is on, locking or unlocking the car shuts the fan down. The fan turns off when the ignition is turned on and the car drives and runs fine otherwise.

Three garages in London, including two Mercedes dealerships with STAR diagnostics, have been unable to isolate the fault. No codes have come up. Battery is also new and is working fine.

I am not sure but I think that it happens when the cabin temperature rises above a certain point. I happen to think so because it usually does not happen at night. All the temperature sensors and Fan control module have been tested and there is no fault code encountered.

Has it happened with anybody else?

Looking for some useful tips.

Regards

 

[grober]

Quite a few cars cooling fans continue to run after shutdown to avoid undue underbonnet overheating but should eventually shut off. I can only sugggest you pull various relevant fuses when the problem is present to see if it goes away.

Mercedes-Benz Fuse Box Diagrams • FuseCheck.com

Fuse box diagrams (fuse layout) and assignment of fuses and relays, location of the fuse blocks in Mercedes-Benz vehicles.

fusecheck.com

 

[KillerHERTZ]

If its doing it until it flattens the battery, check the Termostat which might be at fault.

 

[Petrol Pete]

OP . Welcome , and thank you for thinking we can help you remotely via forum when you have already had the car plugged into not one , but two STAR systems at main MB dealerships, and a 3 garage before that just for good measure.

I am sure , soon enough, one of our members will have a solution having suffered the same fault.

But TWO main dealers using STAR could not find the fault....? ?

 

[MercFault]

OP . Welcome , and thank you for thinking we can help you remotely via forum when you have already had the car plugged into not one , but two STAR systems at main MB dealerships, and a 3 garage before that just for good measure.

I am sure , soon enough, one of our members will have a solution having suffered the same fault.

But TWO main dealers using STAR could not find the fault....? ?

Yes sir, that's right! Two STAR systems could not find the solution as no error code came up.

Since I do not have a knack of car engines, can anyone here please tell me what are the potential ways in which the fan can be triggered? Is cabin temperature one of those? Since the fan usually turns on only when the car is parked in the sun and heat builds up inside the cabin.

Regards

 

[Petrol Pete]

I am no expert on this but it can be triggered by a fault in the aircon system. I had a similar problem with a non MB car. = Start the engine and switch the air con on...within less than a minute long before the engine gets to temperature the main engine cooling fan kicks in and continues to do so as long as the air con is on despite the engine temperature gauge getting no where near the trigger point for the fan to engage.

The main fan is also used to cool the condenser for the air con that is in front of the main radiator . On this car the condenser became almost too hot to touch within a very short space of time , the pressure in the system was high which led my trusted air con guy to deduce a restriction or blockage in the system either in the condenser or the expansion valve.

In this case because of the low value of the car and the fact that the aircon was actually working fairly well I just left it alone, if it pop's , it pop's.

I wouldn't recommend 'letting it pop' as a course of action with your car. I hope this helps.

 

[grober]

We are talking about the engine cooling fan here and not the cabin air circulation fan correct? Has the car aircon been regassed recently? there's usually an inline drier in these A/C systems to mop up water it should be routinely changed with any regas after any leak but is often not done

 

[Petrol Pete]

^^^ Good point Grober , which fan ??

 

[Benzowner]

My son had a similar issue on his car, not a Mercedes, it turned out to be a faulty relay, not sure if Mercedes use relays to control the fan though.

 

[Uky]

The engine cooling fan is connected to a control box that gets a temperature reading from the engine management unit. If the engine temperature is normal and the fan controller has lost the CAN-bus connection - it runs at highest speed to save the engine from overheating. I am unsure if this also happends when everything is shut down, but I would definitley check all connections that runs to the fan control unit. It may be that one of the pins are not properly seated in the plastic housing, or perhaps corrosion as a result of water ingress.

 

[optimusprime]

Yes i had a problem like this on my Volvo V70 ..I never knew about it at the time, that the internal fan ,,, not the radiator cooling fan ,,would operate for a set time after the engine is switched off , and everything shut down. It did this in the hot weather. This was done to cool down the cabin area ,and then switch off after temp was bought down .

 

[optimusprime]

Could be a faulty engine module ... water in the sam or bad plug or socket on the fan itself .Thats if its the engine cooling fan ,,and not the cabin fan .

 

[REDCAPPER]

I have just noticed the same issue on my C200 EQ , it stays on after even short journeys. I take it there is some sort of sensor
for engine temp causing this.

 

[grober]

If your hybrid battery has a liquid cooling system the front cooling fan + circulation pump may continue to run till the battery temp stabilises.

 

[LavandMerc]

Hi everyone, I probably went to the same high rated Mercedes garages in London that MercFault has mentioned and they didn't find what's wrong with my car.

Did anyone find the problem with the fan going full speed after the car is off?? I've been having the same problem from almost an year and I can't find the reason to it. Now I have to wait a few minutes when i turn the car off to make sure the fan doesn't start otherwise it drains my battery. As I said I went to the mechanic several times all the codes were good, they replaced the battery, the cooling sensor and even a few relays but still have the same problem. I think it could even be something linked to the start and stop function as it started being faulty at the same time that the fan started going crazy. The car is a 2013 C Class with 165.00 km. Please share your experience with me as I'm desperate!

 

[optimusprime]

Is it only do this on hot days ? or both hot and cold ?

 

[LavandMerc]

Both hot and cold days

 

[optimusprime]

That tells us there is a problem ..mine did it on hot days only, i found out , that was normal for my car .

 

[Kados]

mimio hace lo mismo lleva 4 meses un c200 sport 2013 pero la desventaja del mio que ya no enciendes el auto, al momento que el auto recibe alguna señal electrica este enciende el ventilador y en la pantalla del estero me sale bloqueo antorobo activado y el auto no enciende para nada alguien mas le ha pasado ?

 

[ALFAitalia]

For those with rusty Spanish...like me!

Mine does the same thing, he has had a 2013 c200 sport for 4 months but the disadvantage of mine is that you no longer start the car, the moment the car receives an electrical signal it turns on the fan and on the stereo screen I get antorobo lock activated and the car It doesn't turn on at all. Has anyone else had this happen to you?