2008 S204 C220Cdi,Radiator Fan Running Full Speed!

[Chrishazle]

Over the past week or so I've noticed the car sounding noisy and a "fan running down" type noise when switching off. No warning lights on dash, took car to local indie this morning, no codes, he thinks the rad fan is shorted out somewhere so shortly after start-up it kicks in at full speed and stays there even when engine has just been started from cold. Dash temperature gauge is accurate (showing 55C when his diagnostic showed 55.3C), and temp gets to 88-90 and stays there so not overheating. Ben tells me it could be in the fan pack and thus a fire risk, so my wallet is trembling, should get a call this afternoon about how big a problem I've got.

Apparently the short could be in one of a number of places - anyone had similar experience to share?

 

[ernie]

Over the past week or so I've noticed the car sounding noisy and a "fan running down" type noise when switching off. No warning lights on dash, took car to local indie this morning, no codes, he thinks the rad fan is shorted out somewhere so shortly after start-up it kicks in at full speed and stays there even when engine has just been started from cold. Dash temperature gauge is accurate (showing 55C when his diagnostic showed 55.3C), and temp gets to 88-90 and stays there so not overheating. Ben tells me it could be in the fan pack and thus a fire risk, so my wallet is trembling, should get a call this afternoon about how big a problem I've got.

Apparently the short could be in one of a number of places - anyone had similar experience to share?

In days gone by when cars were less complicated, without processors, I've had a similar fault due to a failed radiator sensor. Modern cars are a different kettle of fish, though!

Ernie

 

[Chrishazle]

Too **** right Ernie - turns out it's the fan pack that's shorted out, will take a few days to get a replacement from Euro (£100 cheaper and a week quicker than MB) and will cost me £480 fitted! OUCH!!!

 

[ernie]

Too **** right Ernie - turns out it's the fan pack that's shorted out, will take a few days to get a replacement from Euro (£100 cheaper and a week quicker than MB) and will cost me £480 fitted! OUCH!!!

I probably fixed that one for less than a tenner, even at today's rates less than £100!

 

[Chrishazle]

I want to get my hands on the failed bit they take off as I suspect it's just the electronics box that has a failure but you have to buy the complete fan, motor and electronics. There's an outfit called IIRC X8R near me in Folkestone who might be interested in finding a fix for the electronics and add it to the MB parts they already sell - I posted about them recently.

Meet the engineer who fixes what car makers can’t

 

[cheddar]

Have they checked it’s not a faulty AC refrigerant pressure sensor first? These don’t leave an error code normally but register values of hundreds/thousands of bar pressure when they fail.
I have changed many of these on 204’s for these exact symptoms.

 

[Chrishazle]

Thanks Cheddar, I get the feeling you're more than just a member - maybe a secret indie! I've emailed your comment to my Indie, will see what he says!

 

[NDFR]

Here you go I had this problem recently.

W204 radiator fan on full, no aircon

 

[Chrishazle]

Just had a phone call with my indie, he says he checked the aircon pressures etc yesterday with his diagnostic and everything was OK, so it is the fan pack sob sob! There was I hoping it would be a £100 fix rather than £500, looks like I'm out of luck, just have to wait for ECP to get the parts to him - but if that does not cure the problem there will be an interesting discussion!!

 

[cheddar]

Oh dear. Well never mind, at least they have found the fault, nothing worse than being stuck and throwing parts at it until the fault disappears.

 

[Chrishazle]

Interestingly as part of the additional checks he found that there was very little gas in the AC and that it "failed" the vacuum test on a very slow leak, so he's hopeful that the slow leak is due to dry seals that a regas and the oil in the regas will swell the seals and cure that problem. With the sytem degassed he pulled and tested the sensor, and it's fine. However, based on the experience of a member on t'other side with his 219, it suggests that the first port of call for this problem is the AC system, make sure all is kosher on that before looking at the fan pack.

Another thought in my mind is that you should not need to change out a working fan and motor just because the control electronic module has failed, so I'm hoping to rescue the failed one and take it to X8R in Folkestone, not too far from me, to see what they think about offering a refurbed/remade control module for rather less than the £400+ of a full fan pack.

 

[Chrishazle]

First update - it was dry seals on the AC, first re-gas it almost sealed, second one it did. Pretty certain I've not had the AC serviced in the 7 1/2 years I've had the car, so seems it's worthwhile taking advantage of special offers like Groupon/ATS, Kwikfit and even occasionally MB do to have the AC regassed every few years! Also saw a photo of the crap they cleaned out from the bottom of the AC condenser, seems it's a leaves/crap trap, I was amazed how much they'd removed!

Not so good news was that ECP had not yet delivered, so they may not get the new fan pack until tomorrow morning.

 

[Chrishazle]

Car is home and running properly, wallet lightened by £520 - £480 for the diagnostic, supply and fit, £40 for the double AC re-gas. I've got the old fan pack so plan to see what I can see when I remove the 6 torks head screws on the back, with a view to taking it to X8R to see if they could sort a fix for the failed (shorted out) electronic pack inside rahter than replacing fan,motor,shroud etc.