W210 electric/auxiliary fan running erratically

[bob 6600]

Right so after finally sorting the loss of water problem, today I went to Bham to see if the car could do a reasonable motorway run without leaking. All was well on the way. On the way home, i heard a loud noise which sounded like a hole in the exhaust as it got louder at higher revs.

When I got home, I investigated and found it to be the aux fan (the two at the front). It was spinning erratically and I noticed the following.

1. Engine idle - fan off
2. Rev at idle - fan spins very quickly and faster as the revs rise
3. When driving - fan gets faster (louder) as the revs rise and so when there is a gear change, it slows down a bit but picks up speed again.

Now I have never heard this before and it's obviously not working correctly. I will try and do a STAR session tomorrow and get some codes.

What I want to know is what controls this? Is it a separate sensor or the thermostat? Switch? I am tempted to pull the connector for now as it is not required and sounds like an aeroplane trying to take off lol.

As always, any help from the panel are appreciated.

 

[LostKiwi]

They're controlled by a temperature sensor I believe. Tends to suggest you have a hotspot somewhere in the cooling system.

 

[bob 6600]

They're controlled by a temperature sensor I believe. Tends to suggest you have a hotspot somewhere in the cooling system.

please don't say due to a blockage lol

 

[om613]

I was thinking that the K-seal's done some extra work, somewhere around the water way or housing the sender' fits into.

 

[brandwooddixon]

Seems strange that the electric fan speed changes with engine speed.
If it was a temperature related issue then wouldn't the fan run with the engine at idle.

Are you sure that it's not the viscous fan on the engine?

Air drawn by this may make the auxiliary fans turn due to air movement, but not particularly fast. Also from memory, I believe that only one of the two fans has a motor, the other relies on a belt for power.

 

[alexanderfoti]

Seems strange that the electric fan speed changes with engine speed.
If it was a temperature related issue then wouldn't the fan run with the engine at idle.

Are you sure that it's not the viscous fan on the engine?

Air drawn by this may make the auxiliary fans turn due to air movement, but not particularly fast. Also from memory, I believe that only one of the two fans has a motor, the other relies on a belt for power.

I would suspect the other posters are accurate, and that this is a by product of increased voltage with higher revs.

 

[bob 6600]

Don't think the viscous has anything to do with it. It seems to be running correctly.

Will get it on STAR later today when I get a chance

 

[bob 6600]

OK STAR session done, it showed up B1231 Coolant Temperature sensor B11/4 comes from engine control module. This to me is the sensor on the top of the radiator. I cleared the code and it didn't come back but the fault is there so may replace it anyway.



I also did a test/actuation on the aux fan and it does nothing. Confused

 

[LostKiwi]

Have you checked the temperatures reported by each of the temperature sensors? You can check them in STAR.

The way it works is the fans will operate with aircon on low speed or when a temperature sensor (and can't remember which as there are a few) passes a threshold. If the temperature continues to increase the fan will switch to high speed.

If you have AAC you can enter diagnostics for the A/C controller and view what the A/C controller is telling the fans to do.

 

[bob 6600]

The thermostat sensor seems to be reporting the correct temp, i haven't found the other one yet, will be my mission tomorrow!

I do recall a sensor on the fan housing area, which corresponds with EPC as being the temp switch/sensor. Looks like this

I do have AAC and yes forgot about it's on board diagnostics. Something else i will have to check. I do recall the above switch having some water corrosion on the contacts when I took it all apart when doing the water pump few months back. I did clean it up but could be now gummed up.

 

[om613]

OK STAR session done, it showed up B1231 Coolant Temperature sensor B11/4 comes from engine control module. This to me is the sensor on the top of the radiator. I cleared the code and it didn't come back but the fault is there so may replace it anyway.



I also did a test/actuation on the aux fan and it does nothing. Confused

There's probably this sensor still present in my spare rad.
Yours FOC if you want, Bob?

 

[bob 6600]

There's probably this sensor still present in my spare rad.
Yours FOC if you want, Bob?

Yes please if you wouldn't mind

 

[mersum1es]

I was getting coolant visit workshop message in my W210, fan was working but never at high speed. I made the test above, and lower fan speeds were working ok but when I went above 50% speeds fault was triggered and fan lowered at idle speed. Culprit was fan control module (located inside bumber). It sounds it might be your issue too.

 

[bob 6600]

I was getting coolant visit workshop message in my W210, fan was working but never at high speed. I made the test above, and lower fan speeds were working ok but when I went above 50% speeds fault was triggered and fan lowered at idle speed. Culprit was fan control module (located inside bumber). It sounds it might be your issue too.

Inside front bumper? I have taken it apart before and cannot recall anything there?

 

[mersum1es]

it is located above fog light, attached to frame, can be accessed underneath. Don't know if it is revealed when bumber removed (never removed mine)

https://ww2-secure.justanswer.com/uploads/eurotec/2012-05-18_232821_capture.png

 

[om613]

I've taken a few front bumpers off 210s. Never seen any modules nearby or adjacent, though.

 

[bob 6600]

I can't remember seeing one, and I've had mine off a few tines as well as the headlamps. I'll look in the wing or try and follow the harness from the fan back. Not today though, it's freezing! lol

 

[bob 6600]

Small update...

I disconnected the electric fan for a temp fix and IT STILL RUNS! Thinking I had gone mad I tried to troubleshoot and had an idea that there is air being forced towards the fan making it spin. Stupidly I eliminated the viscous fan but have realised that it is running a lot quicker than before and with engine speed. This causing enough air to make the aux fan spin. So, it looks like the viscous fan has failed!

 

[om613]

They don't need the mech fan, anyway. Mine's been off for ages, nil effect.

 

[LostKiwi]

Viscous fan was deleted on later cars. My 210 has never had one.