ML350 Radiator Fan is on high speed - PeachParts Mercedes-Benz Forum

mbcollin · #1 09-04-2008, 07:22 PM

I have 2006 ML350 and the radiator fan is on high speed and making noise like a jet engine even thought the engine is not hot (85 degree outside). I took it to dealer and the service advisor told me that it is a normal that Mercedes models have loud fan noise and everything checked out OK.

The high fan speed occurs after I drove for about 20 to 25 minutes. Once the fan is on high speed, it does not change to lower speed.
In common sense, the fan is to lower the temperature, so it should be on when it is hot and shut off or blow in a lower speed when it is cool down. It should be operated on a varying speed, but it is on a high speed all the time. I am thinking some sort of thermostat, which controls the fan speed is not working properly.

It is my challenge to convince my service advisor to agree on the common sense.
Does anyone have a similar issue with the fan speed on ML350?

Carson357 · #2 09-04-2008, 11:33 PM

does it happen with a/c on and off?

mbcollin · #3 09-05-2008, 12:38 AM

It happens with AC on. Once the fan is on high speed, it stays on and generates jet engine noise.

reprobate · #4 09-05-2008, 10:07 PM

My CLK 320 has just started doing this. Turn off the AC and the fan either shuts down or goes into low speed. Didn't do it last month. I haven't taken it to the shop, I have a trip to finish first.
Carl

KAMA · #5 07-27-2019, 08:13 AM

My GL 450 2013 model does same , anyone with the idea of what’s wrong ?

lsmalley · #6 07-29-2019, 12:10 AM

Quote:

Originally Posted by KAMA

My GL 450 2013 model does same , anyone with the idea of what’s wrong ?

Check fan relay or temp sensor

tjts1 · #7 08-02-2019, 11:36 AM

The electric fan is pwm controlled by the ECU. When the fan loses contact with the ECU it's failsafe mode is full speed. Better to burn out the electric fan motor then overheat the engine.