Rad cooling fan operation

[Jenny Tills]

Hi guys, I am the proud owner of a 2013 CLS 350 cdi.
Just lately, in the cold weather, I have been having the radiator fan blowing away like it's a hot summer day. At first I put it down to a DPF regen, but every time the outside temperature is freezing or below, the fan has been on.
The interior heater is fine, nice and toastie, and the temperature gauge is pointing at the lowest number on the dial. 40.
Yesterday it was +8 degrees and the gauge was pointing at or around 60.
Any help, advice, is very welcome.
Many thanks in advance.

 

[Jenny Tills]

Hi guys, I am the proud owner of a 2013 CLS 350 cdi.
Just lately, in the cold weather, I have been having the radiator fan blowing away like it's a hot summer day. At first I put it down to a DPF regen, but every time the outside temperature is freezing or below, the fan has been on.
The interior heater is fine, nice and toastie, and the temperature gauge is pointing at the lowest number on the dial. 40.
Yesterday it was +8 degrees and the gauge was pointing at or around 60.
Any help, advice, is very welcome.
Many thanks in advance.

 

[Blobcat]

I’ve merged your threads for you as there’s no need to post the same question multiple times.

Might be worth getting codes read by a Mercedes specific code reader to see what if anything is logged

 

[Jim2]

Hi guys, I am the proud owner of a 2013 CLS 350 cdi.
Just lately, in the cold weather, I have been having the radiator fan blowing away like it's a hot summer day. At first I put it down to a DPF regen, but every time the outside temperature is freezing or below, the fan has been on.
The interior heater is fine, nice and toastie, and the temperature gauge is pointing at the lowest number on the dial. 40.
Yesterday it was +8 degrees and the gauge was pointing at or around 60.
Any help, advice, is very welcome.
Many thanks in advance.

To you mean engine temp? or external temp? The engine is designed to run at a certain temperature, and its controlled by thermostats. So all being well, you could be driving in -15c externally, but the cabin would be as you describe it " Toastie". As Blobcat suggests, a scan would be the first course of action to follow.

 

[Jenny Tills]

This is about engine coolant temps. Thanks for your advice, I will be taking it to a garage for some diagnostic checks.

 

[mattkh]

This is about engine coolant temps. .

In that case I do not see anything wrong with your car. The engine coolant temperatures reflect the various parameters involved.

 

[Jim2]

In that case I do not see anything wrong with your car. The engine coolant temperatures reflect the various parameters involved.

Yes, but I think was worrying her was the fact that even in sub -zero temperatutres, the radiator fan was running on, and at first she thought that it was doing a regen, but then it was continually happening, and she got a bit worried , In hot weather, I've seen engine fans running after the engine was switched off , to bring the temp down,,,but in zero temps? Something not right there I think. A scan will clear it up though.

 

[B king]

hi , , ive had exactly the same problem on my e350, fans blowing on very cold mornings....i had to stop the engine , remove the key , wait for the ecu to reset and then restart, all would be well , the strange thing was this never happens in the summer , only when v cold .I metioned this to my indi service cntr who have the latest star system, and basically , they had no idea ..it showed nothing , metioned again at the next service and star metioned a valve to do with cooling so i said swap it ..so 300 quid later , no different..Your engine should run at way more than 60 degrees mine was just the same , i have just changed the thermostat , and now it runs at 92 degrees....and so far ,the fan is behaving .I am told that many errors can result in the engine fan coming on as a saftey precaution, but this means the fitters seem to be guessing whats wrong and you just keep replacing parts that maybe ok .

 

[Jim2]

In a previous car of mine ( Audi A6 ) the fan was sometimes very erratic, running when it should not, and vice versa. Finally tracked it down to a sensor within the bottom radiator hose. Changed the sensor, and that was that. No more fan problems. But a car running at 60c, is a definite indication of a thermostat problem. In the case of intermittent faults, sometimes a scanner will not recognise it as a fault, and wont log it.

 

[Jenny Tills]

Thanks very much guys. Hopefully it's a thermostat. Hopefully a straightforward job and about £50 to replace.

 

[Jim2]

Thanks very much guys. Hopefully it's a thermostat. Hopefully a straightforward job and about £50 to replace.

Hopefully it's just a bad electrical connection, or faulty sensor. My bet is a sensor.

 

[norwoodboy]

Sounds like the Thermostat has locked open and needs replacing, if it is around £120 OEM + labour.

 

[Jenny Tills]

Hi guys, and thank you all very much.
So my problem was indeed the thermostat. A massive thank you to the knowledgeable folk at MB in Shrewsbury.
As if by magic the check engine light came on the night before visiting Mercedes, so I guess it made their job easier? I don't know.
The morning I dropped her off it returned 30mpg after a 30 mile slow drive. When I parked up outside my house that same evening, it said 44mpg.
Normal service is resumed!
Once again many thanks to all contributors.