SL/R230: Engine Fan Noise
Thread Starter
Member
Joined: Jan 2015
Posts: 77
Likes: 24
2021 GLE450
Engine Fan Noise
I have a 2007 SL550 that I bought used a while back and ever since I have owned the car the radiator fan comes on and is really loud. This starts about 30 seconds after the car is started, even when the engine is cold (it can be below freezing and the fan still come on. I have had it to my Mercedes dealer and they tell me it is normal. I was wondering if any of you have the same thing. Is seem to me the fan should come on when the engine heats up or if I have been driving for a while. It is kind of embarrassing as the fan noise is really noticeable. I have replaced the thermostat assembly and that did not change things. Any ideas on what could cause this?
Junior Member
Joined: May 2014
Posts: 58
Likes: 3
From: South Beach & Texas
SL 600
My SL600 did the same for a few days then an error message came up, "Visit Shop" or something to that affect. Notice a few days later the sound went away but so did the fan. Engine fan stopped working so I replaced engine fan all good, no message.
Member
Joined: Jun 2014
Posts: 238
Likes: 16
From: Chandler, AZ
2003 SL500, 2016 ATS, 2016 CTS 2015 Volt
I have a 2007 SL550 that I bought used a while back and ever since I have owned the car the radiator fan comes on and is really loud. This starts about 30 seconds after the car is started, even when the engine is cold (it can be below freezing and the fan still come on. I have had it to my Mercedes dealer and they tell me it is normal. I was wondering if any of you have the same thing. Is seem to me the fan should come on when the engine heats up or if I have been driving for a while. It is kind of embarrassing as the fan noise is really noticeable. I have replaced the thermostat assembly and that did not change things. Any ideas on what could cause this?
Thread Starter
Member
Joined: Jan 2015
Posts: 77
Likes: 24
2021 GLE450
Thanks next2pool, I have noticed this function as well. When I turn on my AC, the fan runs faster, and when I shut it off it quiets down. The thing is, it seems to be running a lot more than it should. I would think with the AC off and a cold engine (32 degrees), the fan would not come on until the engine is at least up to temp. In my case regardless of engine temp the fan will come on in about 30 seconds and never shut off, just speed up when the AC is on and slow down when I shut it off.
Member
Joined: Jun 2014
Posts: 238
Likes: 16
From: Chandler, AZ
2003 SL500, 2016 ATS, 2016 CTS 2015 Volt
Thanks next2pool, I have noticed this function as well. When I turn on my AC, the fan runs faster, and when I shut it off it quiets down. The thing is, it seems to be running a lot more than it should. I would think with the AC off and a cold engine (32 degrees), the fan would not come on until the engine is at least up to temp. In my case regardless of engine temp the fan will come on in about 30 seconds and never shut off, just speed up when the AC is on and slow down when I shut it off.
Senior Member
Joined: Jul 2015
Posts: 355
Likes: 41
From: amarillo texas
2003 sl 500
This may be a thermal detector switch, wherever that may be, is bad and is sending an erroneous value to the car computer to activate the fan at the wrong speed. Just my guess but I would think some switch like that seems plausible to control fan speed. Let us all know what comes out of your work as this could help us all for a buggy problem like this
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Thread Starter
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Joined: Jan 2015
Posts: 77
Likes: 24
2021 GLE450
I have finally found the problem with my radiator fan running at high speeds. A local technician (Eurosports of Wayzata) found that a mouse had made a nest in the front of the car and chewed through some wires that were causing erroneous temperatures on the car. Once the wire were repaired the fan runs normally now. The wires were located in the front of the car on the passenger side. Now when I pull up to a stop sign it doesn't sound like a jet engine waiting to take off.
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Newbie
Joined: Jun 2020
Posts: 10
Likes: 0
From: Georgia, USA
2012 Mercedes E350 Bluetec
That is definatelly not normal. Fan shoud come on to maintain the normal operating temp or AC call. My E350 started doing that and like yours it comes on about 15 sec after engine starts and stays on about 1 minute after the car is shut off completely. In my case I get a codes 10c100 and 10C200 which suggests short circuit at the fan lavel but I did not fix it yet so I can't confirm that that is actually the issue. I will update my post once I fix it.
