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W212 AMG Discuss the W212 AMG's such as the E63

Fan running constantly...

     
Old Dec 16, 2020 | 07:10 PM
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Fan running constantly...
As the title says...i noticed that the fan was running when i pulled into the garage at lunch. I wasnt running the car hard and it was around 40 degrees out, so I found it odd. When I get in the car to go back to work, a couple of hours later, the fan immediately turns on. And stays on. I park the car outside for a 4 hours...jump back in to come home....fan comes right back on at startup and stays on til i get home. Any ideas what this may be? Bad relay?

or....is this normal and I just never noticed it?

Any help would be much appreciated!
Last edited by 1MavRick; Dec 16, 2020 at 07:17 PM.
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Old Dec 16, 2020 | 08:03 PM
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Originally Posted by 1MavRick
As the title says...i noticed that the fan was running when i pulled into the garage at lunch. I wasnt running the car hard and it was around 40 degrees out, so I found it odd. When I get in the car to go back to work, a couple of hours later, the fan immediately turns on. And stays on. I park the car outside for a 4 hours...jump back in to come home....fan comes right back on at startup and stays on til i get home. Any ideas what this may be? Bad relay?

or....is this normal and I just never noticed it?

Any help would be much appreciated!
Try toggling the AC/defrost settings or killing the HVAC altogether, could be the condenser fan coming on? If radiator fan maybe a temp sensor issue. Just spitballing.

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Old Dec 16, 2020 | 09:44 PM
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Originally Posted by NoVAe63s
Try toggling the AC/defrost settings or killing the HVAC altogether, could be the condenser fan coming on? If radiator fan maybe a temp sensor issue. Just spitballing.
turned the HVAC completely off....still running. it looks to have sufficient coolant in it, as well. where can i find the IC reservoir?
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Old Dec 16, 2020 | 10:04 PM
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I asked a similar question before and I was told it might be the LED light fan. Delayed shutoff and immediate turning on. I think it’s normal.
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Old Dec 16, 2020 | 10:27 PM
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The IC coolant tank is in the middle of the engine, under the middle engine cover, just pull it up and off from the front first and the rear corners.
The fan will run if IAT are high.
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Old Dec 16, 2020 | 10:35 PM
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Originally Posted by 1MavRick
turned the HVAC completely off....still running. it looks to have sufficient coolant in it, as well. where can i find the IC reservoir?
Expansion tank on the divorced systems is right next to the ECU I believe. Pre-divorced systems share the engine coolant loop.
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Old Dec 16, 2020 | 10:38 PM
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Originally Posted by NoVAe63s
Expansion tank on the divorced systems is right next to the ECU I believe. Pre-divorced systems share the engine coolant loop.
ok. I took the engine cover off and didn’t see anything. Figured it was because I have a ‘12. Thanx for help. Guess I’ll take it to the shop in the morning. Merry Christmas to me!!!
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Old Dec 16, 2020 | 11:02 PM
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Originally Posted by 5soko
The fan will run if IAT are high.
which would rule that out as the fan turns on right at startup after being parked outside on a chilly day, no?
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Old Dec 16, 2020 | 11:25 PM
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Originally Posted by 5soko
The IC coolant tank is in the middle of the engine, under the middle engine cover, just pull it up and off from the front first and the rear corners.
The fan will run if IAT are high.
same coolant goes in there as the radiator?
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Old Dec 17, 2020 | 07:46 AM
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Originally Posted by 1MavRick
which would rule that out as the fan turns on right at startup after being parked outside on a chilly day, no?
yes for sure! If you have a code reader like icarsoft that reads all modules, give it a scan.



Originally Posted by Mojo20032004
same coolant goes in there as the radiator?
Small IC coolant tank fluid in the middle doesn't go into engine radiator, it is Separate.
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Old Dec 17, 2020 | 07:56 AM
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Originally Posted by 5soko
yes for sure! If you have a code reader like icarsoft that reads all modules, give it a scan.




Small IC coolant tank fluid in the middle doesn't go into engine radiator, it is Separate.
​​​​​​I'm aware of that, I'm asking is it the same kind of coolant or is it diffrent?
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Old Dec 17, 2020 | 09:23 AM
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Originally Posted by Mojo20032004
​​​​​​I'm aware of that, I'm asking is it the same kind of coolant or is it diffrent?
Ahh ok, yes. It is the same coolant
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Old Dec 17, 2020 | 09:29 AM
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Ok. So I checked to see if there’s a fault code on Torque Pro. Here’s what I got...



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Old Dec 17, 2020 | 09:38 AM
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Also....something I just noticed....the ECO mode no longer works. Turn the car off...turn it back on...and it’s lit up green. Right around the time the fan comes on....5-10 seconds...the light goes off. So it’s probably an ECU, huh?
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Old Dec 17, 2020 | 11:43 AM
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Originally Posted by 1MavRick
Also....something I just noticed....the ECO mode no longer works. Turn the car off...turn it back on...and it’s lit up green. Right around the time the fan comes on....5-10 seconds...the light goes off. So it’s probably an ECU, huh?
Not ecu, but engine coolant sensor might have a short, or went bad
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Old Dec 17, 2020 | 11:44 AM
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Originally Posted by Mojo20032004
Not ecu, but engine coolant sensor might have a short, or went bad
im sitting at the shop, as I type, waiting for the diagnosis. Wish me luck!
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Old Dec 17, 2020 | 01:03 PM
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Temperature sensor is going bad and causing fan faults. They reset it and it’s working correctly, for now. But the part has been ordered and we will get it resolved next week.

Thanx so much to everyone’s help and advice.
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