06 CLk350 engine fan loud as hell+AC stopped working..
05-28-2017, 09:27 PM
#1
Junior Member
Thread Starter
06 CLk350 engine fan loud as hell+AC stopped working..
Happy Memorial Day weekend everyone! hope your benz is treating you better than mine lol..
Anyways my AC recently stopped working completely and in addition my engine fan always turns on now (and its crazy loud!) as soon as i turn on the car until i shut it off.. This all happened out of the blue random as hell and whats weird is both of these things happened at the same time.. no CEL or messages on the screen (though i havent used a scan tool yet so who knows what that will tell me..) anyways Im just looking for some insight to why this has happened..
(Oh and btw the weather here has been very good! usually mid 70s and the oil temp has been normal too!)
Anyways my AC recently stopped working completely and in addition my engine fan always turns on now (and its crazy loud!) as soon as i turn on the car until i shut it off.. This all happened out of the blue random as hell and whats weird is both of these things happened at the same time.. no CEL or messages on the screen (though i havent used a scan tool yet so who knows what that will tell me..) anyways Im just looking for some insight to why this has happened..
(Oh and btw the weather here has been very good! usually mid 70s and the oil temp has been normal too!)
05-28-2017, 09:58 PM
#2
MBworld Guru
The ECU control the suction fan based on it's interpretation of demand from the temperature sensor inputs and the operation of the AC. If it runs on high from start, that means that either the ECU can no longer communicate with the fan's controller module (so the fan goes into high as a safe default), or the ECU can't communicate with a temperature sensor, so it runs the fan on high, again as a safe default. If the ECU can't communicate with the fan, it's probably a bad fan controller.
I am not certain, but the AC may be disabled if the ECU can't talk to the fan, also for safety in keeping the engine cool. With SDS, you can test all this. I'm not sure about using a generic scanner. You might try unplugging the fan wiring harness and spraying it with contact cleaner.
I am not certain, but the AC may be disabled if the ECU can't talk to the fan, also for safety in keeping the engine cool. With SDS, you can test all this. I'm not sure about using a generic scanner. You might try unplugging the fan wiring harness and spraying it with contact cleaner.
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zejj (05-28-2017)
05-28-2017, 10:13 PM
#3
Junior Member
Thread Starter
The ECU control the suction fan based on it's interpretation of demand from the temperature sensor inputs and the operation of the AC. If it runs on high from start, that means that either the ECU can no longer communicate with the fan's controller module (so the fan goes into high as a safe default), or the ECU can't communicate with a temperature sensor, so it runs the fan on high, again as a safe default. If the ECU can't communicate with the fan, it's probably a bad fan controller.
I am not certain, but the AC may be disabled if the ECU can't talk to the fan, also for safety in keeping the engine cool. With SDS, you can test all this. I'm not sure about using a generic scanner. You might try unplugging the fan wiring harness and spraying it with contact cleaner.
I am not certain, but the AC may be disabled if the ECU can't talk to the fan, also for safety in keeping the engine cool. With SDS, you can test all this. I'm not sure about using a generic scanner. You might try unplugging the fan wiring harness and spraying it with contact cleaner.
could you show me where the fan controller/ wiring is? i googled M272 fan controller and M272 fan wiring harness but couldn't find any pictures...
05-29-2017, 11:54 AM
#4
MBworld Guru
The fan control module is part of the fan unit itself. There is a single large connector that plugs into the fan - undo that and check for corrosion or abrasions on the wiring.
06-29-2018, 10:43 AM
#5
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E350
E350 Fan On High
hello dear Mercedes drivers, i am from Germany and bought me a e350 US Import car, i have a Problem.
my car has a premair sensor on the Radiator.
i replaced my Radiator and paste a Radiator that is not suitable for my car because it hasn‘t a premair Sensor plate integrated.
My Fan is Not Running all the Time but it runs often and on high speed...
can it be cause of the premair Sensor ?
The premair sensor i didn‘t replaced At all, so the new ohne is with the old plate that was in the old Radiator now in the new radiator, i pressed it inside
can the Sensor fail cause of that? And is it possible that the Fan runs ?
Please help me, in Germany no one knows the Problem ......
my car has a premair sensor on the Radiator.
i replaced my Radiator and paste a Radiator that is not suitable for my car because it hasn‘t a premair Sensor plate integrated.
My Fan is Not Running all the Time but it runs often and on high speed...
can it be cause of the premair Sensor ?
The premair sensor i didn‘t replaced At all, so the new ohne is with the old plate that was in the old Radiator now in the new radiator, i pressed it inside
can the Sensor fail cause of that? And is it possible that the Fan runs ?
Please help me, in Germany no one knows the Problem ......
06-29-2018, 09:49 PM
#6
MBworld Guru
The fan is controlled by the ECU. If the fan does not get a signal from the ECU, it defaults to high speed. Since you removed the fan for the radiator replacement, I would check the fan's wiring connections.
