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?

 

[LostKiwi]

My 129 did this when it had low AC pressure. Regassed and all sorted.

 

[Chrishazle]

Funnily enough, Ben did mention the AC as apparently the AC uses the same rad as the engine - but he turned the AC off and the problem was still there, so I think he's discounted the AC.

 

[LostKiwi]

Funnily enough, Ben did mention the AC as apparently the AC uses the same rad as the engine - but he turned the AC off and the problem was still there, so I think he's discounted the AC.

Turning off the AC on the 129 made no difference. The only way I could stop it (until regassed) was to remove the AC fuse from memory.

 

[Chrishazle]

Thanks Alastair, I'll pass your comment on to Ben. AFAIK my AC is working well.

 

[alexanderfoti]

Rad fans running at full speed happens for a few reasons on MB's. As others have said, it can be caused by very high ac pressure, but if the ac is switched off, it's not that.

They also run full speed when they lose communication with various control modules (engine ecu, gearbox ecu on some, climate control module etc) as a failsafe. In addition, if some sensors are unplugged (coolant temp sensor etc) then that can cause it.

If it only happens on ignition on then I suspect its one of those.

 

[Chrishazle]

Well, I have the answer, and my wallet just had a heart attack! It's the fan pack shorted out, MB can't get one until next week sometime, Euro have one but it's in Crawley (and about £100 cheaper then MB) and until they order the part tomorrow morning we don't know how quickly they can get it to Ashford. It's going to cost £480 fitted and we won't get the car back until Thursday late afternoon at the earliest, possibly Friday or even Saturday depending on how quickly Euro get the part to them!

OK, it's only the second mechanical gremlin other than wear and tear parts (tyres, brake pads/discs, servicing) in 7 1/2 years and about 45-50k miles ownership, but it's still a large unexpected lump of cost. Typical reaction from SWMBO though - is the age/mileage of the car starting to be expensive (in other words is it time to change). She did this to me years ago with our Rover 827 Vitesse when it got close to 100k miles - despite the car being in excellent condition and running like a sewing machine, made me sell it, replaced it with a Rover 820 turbo vitesse and dropped £8k when we chopped that in a year later.

Oh well, that puts the paintwork repair back another month or two, as that will be another £600 for the roof and bonnet respray due to peeling lacquer. Just hope she does not want to go anywhere until we get the MB back as, with the weather forecast, I'm not keen to get the 968 cab out, and a big supermarket shop with that would be "interesting"!!

 

[Chrishazle]

Thanks Alex, I was typing my update when you posted so have just seen it. Ben is certain that it's the fan pack, he ran quite a diagnostic while I was down there - don't know exactly what he used, I know he has Star but he's commented to me in the past that it's the last diagnostic tool he uses even on an MB as other tools give him quicker and better information. All I saw was he used a code reader wireless linked to a tablet he was holding.

 

[alexanderfoti]

Good to hear its diagonsed, Fan controller isnt a common issue on these but glad its sorted ish.

 

[Chrishazle]

I'm planning to ask for the old failed item to take to X8R in Folkestone, as my guess is it's just the electronics failed, but you have to buy the whole fan/motor/electronics in one go. Maybe they can add a repair kit to the MB parts they already do :

https://www.msn.com/en-gb/cars/news...s-cant/ar-AAI0xxW?li=BBoPJKX&ocid=mailsignout

Interesting that on the ECP website the full price of a fan pack is similar to MB's price, if not a bit higher, but with the current discount code the price drops £160 to about £100 less than MB!

 

[alexanderfoti]

I'm planning to ask for the old failed item to take to X8R in Folkestone, as my guess is it's just the electronics failed, but you have to buy the whole fan/motor/electronics in one go. Maybe they can add a repair kit to the MB parts they already do :

https://www.msn.com/en-gb/cars/news...s-cant/ar-AAI0xxW?li=BBoPJKX&ocid=mailsignout

Interesting that on the ECP website the full price of a fan pack is similar to MB's price, if not a bit higher, but with the current discount code the price drops £160 to about £100 less than MB!

That's euro car part's business model. Everything on their site is 30-50% overpriced, and they always have a discount code or 5 available

Have used X8R's parts many times (Keyless door buttons and lock kits for 203's)

 

[Chrishazle]

Another interesting comment from t'other side :

"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"

I've emailed this to my indie and will see what he says - I get the impression that the poster (Cheddar) may be a "secret indie" as looking at some of his other posts he appears more knowledgeable etc that your ordinary enthusiast member!

 

[Cole@MBS]

We do a lot of 204, 212 and 207s for pressure sensors, 99% of the time it’s that little sucker!!

 

[Chrishazle]

Thanks Cole, I'll speak to Ben (MTA Networks, previously known as Mastertech Automotive) in the morning, and have just emailed him (as I did for Cheddar's reply on t'other side) saying fitting a new fan pack and the problem remaining will lead to an "interesting" discussion, as I'm guessing that a replacement pressure sensor will be rather less than £480 fitted!!

 

[Chrishazle]

https://forums.mbclub.co.uk/threads/w204-radiator-fan-on-full-no-aircon.253529/

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!!

 

[Chrishazle]

My 129 did this when it had low AC pressure. Regassed and all sorted.

Just an update, he put his AC regas machine on the car today (after emailing him the various responses I've had on here and t'other side from respected indies and members who have had the same problem), it had very little gas in it and failed the vacuum test on a very slow leak, which he's hoping is dry seals and will be cured by the oil in the regas. While degassed he pulled and tested the pressure sensor and it was fine. Don't know if he can regas and start the engine ATM as he has the fan pack almost ready to remove, and should get the new fan pack tomorrow, but it makes me think that the first port of call for the continuous high speed fan problem should be to fully test the AC system and ensure it is totally kosher before going for the expensive fan pack change.

FWIW Ben is adamant that his diagnostics confirm that it's the fan pack not the AC, and he's very knowledgeable about such things - and for sure I do not have the knowledge to query that, just the credit card to pay the bill!!

 

[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.

 

[LostKiwi]

I take it the regas didn't sort the fan then...

 

[Chrishazle]

I asked that question, answer was that the fan was disconnected at the time (and still is awaiting the new pack). In showing me the video of the crap that they cleaned from the AC condenser he also showed me the fan plug hanging down loose!

 

[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.