Radiator Fan
04-12-2018, 08:02 PM
#1
Member
Thread Starter
Radiator Fan
2007 CLK350 cab
Recently my radiator fan comes on at high speed (sounds like an airplane) without the AC on. It’s been like 40 degrees Fahrenheit outside. The car temperature is normal at around 80c.
the fan comes on while driving or stopped at a light turns off for about a minute or two and then starts again. i use to only hear the fan come on when the AC would be on max. Any suggestions?
Recently my radiator fan comes on at high speed (sounds like an airplane) without the AC on. It’s been like 40 degrees Fahrenheit outside. The car temperature is normal at around 80c.
the fan comes on while driving or stopped at a light turns off for about a minute or two and then starts again. i use to only hear the fan come on when the AC would be on max. Any suggestions?
04-12-2018, 10:20 PM
#2
MBworld Guru
This means on of two things: Either the fan control module (built onto the fan) is not communicating with the ECU, or the engine temperature sensor is not reporting. In either case, the fan will go into default high-speed mode. I'd pull codes to see which it is.
04-13-2018, 01:02 AM
#3
Member
Thread Starter
Thanks for the reply, I tried pulling codes but no codes were present. If it was one of those two should I have received a code?
If it’s the control module can it be replaced or does the whole fan have to be replaced?
also do you know where the engine temperature sensor is located exactly?
If it’s the control module can it be replaced or does the whole fan have to be replaced?
also do you know where the engine temperature sensor is located exactly?
04-13-2018, 09:04 PM
#4
MBworld Guru
Here's the coolant temp sensor:
http://benzbits.com/M272/CoolantTempSensor.pdf
The fan controller is integrated into the motor, and it only comes as a complete unit with the fan.
http://benzbits.com/M272/CoolantTempSensor.pdf
The fan controller is integrated into the motor, and it only comes as a complete unit with the fan.
04-19-2018, 11:21 PM
#5
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Thread Starter
I haven’t had a chance to start working on this, but I will most likely this weekend if the weather is good. My question is if it’s either one of those two things you mentioned, should the check engine light have lit up by now? Cause as of right now no check engine light.
04-20-2018, 09:55 PM
#6
MBworld Guru
This happened on my SL550 - the fan would run on high, and even keep running after shutting the car off. The MIL was not illuminated, but there was a code stored for the temperature sensor. I unplugged it, sprayed the connector with CRC contact cleaner, and all is well. I'm not sure if it was loos or maybe had some oil from a leaky centrifuge cover, but that seemed to fix it.
04-22-2018, 01:53 PM
#7
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Thread Starter
So I attempted to get to the temperature sensor but had no success. I’m attaching a picture let me know if I’m looking in the right area. I put an arrow where I was trying to stick my hand through to see if I can locate the sensor.
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04-25-2018, 06:25 PM
#9
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Thread Starter
So I was able to locate and change the sensor. When I took the sensor out a lot of anti freeze ended up coming out. after changing the sensor now my car doesn’t start, I pulled codes and I have a pending P0335. I kept trying to start the car and eventually it will start but after a minute or two it would shut off.
p0335 is the crankshaft sensor but it doesn’t make sense to me how that went bad right after I changed the temperature sensor.
Can you let me know where that sensor is located and what insight you might have on this.
p0335 is the crankshaft sensor but it doesn’t make sense to me how that went bad right after I changed the temperature sensor.
Can you let me know where that sensor is located and what insight you might have on this.
04-25-2018, 10:13 PM
#11
Member
Thread Starter
Thanks!
that looks like it’s going to be tough to get to. I’m thinking when the antifreeze was spilling out from the temperature sensor it must have ruined this one.
Maybe i can get to it through the bottom of the car. I’ll take a look tomorrow.
that looks like it’s going to be tough to get to. I’m thinking when the antifreeze was spilling out from the temperature sensor it must have ruined this one.
Maybe i can get to it through the bottom of the car. I’ll take a look tomorrow.
04-26-2018, 03:14 PM
#12
Member
Thread Starter
Update:
i was able to changed the crankshaft sensor car that seems to be fixed now. The fan was still coming on at high speeds randomly after the temperature sensor was replaced but for the past hour of driving it hasn’t so maybe it corrected itself. Time will tell.
i rescanned the car and now I’m getting another pending code P0106 (map sensor) can you tell me where that is located... also how is it that these codes are coming up now... I fix one thing and then another one pops up right after, not making sense.
As always Rudeney your help is always appreciated!
i was able to changed the crankshaft sensor car that seems to be fixed now. The fan was still coming on at high speeds randomly after the temperature sensor was replaced but for the past hour of driving it hasn’t so maybe it corrected itself. Time will tell.
i rescanned the car and now I’m getting another pending code P0106 (map sensor) can you tell me where that is located... also how is it that these codes are coming up now... I fix one thing and then another one pops up right after, not making sense.
As always Rudeney your help is always appreciated!
04-27-2018, 05:09 PM
#14
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Thread Starter
I fixed the p0160 code it ended up being a tear in the vacuum hose... I was hopeful that by changing the temperature sensor that my fan would stop coming on in high speed when it wasn’t needed but today it started happening again.
from the research I have been doing in the forums I’m seeing it could be the fans control module or the ecm/ecu. Is there a way for me to test which one it will be before replacing the parts. Both seem to be expensive.
from the research I have been doing in the forums I’m seeing it could be the fans control module or the ecm/ecu. Is there a way for me to test which one it will be before replacing the parts. Both seem to be expensive.
04-27-2018, 09:55 PM
#15
MBworld Guru
It can be properly diagnosed with SDS. I doubt it's the ECU or you;d have other issues. It still could be a wiring problem between the ECU and temp sensor or ECU and fan.
04-28-2018, 01:26 PM
#16
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Thread Starter
Here’s one thing I noticed today. When the fan kicks in at high speed and I then turn the ac on high let it run for about 25 seconds and then turn it off the fan stops aswell. And then it starts back on a maybe 2-3 minutes later. I don’t know if this helps with but it’s something I noticed.
05-13-2018, 10:09 AM
#17
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Thread Starter
I tried plugging in a new fan to see if it’s possibly the control module but that wasn’t it. I had someone plug in their star diagnostic and they said they saw an open circuit and they beleive that it’s the ecu. They are suppose to be coming back with an ecu (not cloned) to put on my car and see if the fan comes on when the key is in 2nd position. They said if the fan doesn’t come on at that point then it’s definitely the ecu. Does that make sense?
05-13-2018, 10:32 AM
#18
MBworld Guru
Here’s one thing I noticed today. When the fan kicks in at high speed and I then turn the ac on high let it run for about 25 seconds and then turn it off the fan stops aswell. And then it starts back on a maybe 2-3 minutes later. I don’t know if this helps with but it’s something I noticed.
It sounds like the fan is operating normally with the AC function.
I tried plugging in a new fan to see if it’s possibly the control module but that wasn’t it. I had someone plug in their star diagnostic and they said they saw an open circuit and they beleive that it’s the ecu. They are suppose to be coming back with an ecu (not cloned) to put on my car and see if the fan comes on when the key is in 2nd position. They said if the fan doesn’t come on at that point then it’s definitely the ecu. Does that make sense?
Did you note the DTCs reported by SDS? The test to see if the fan runs on high with another car's ECU installed will tell you nothing except that the fan controller is functioning properly. Whenever the fan controller fails to get a signal form the ECU, it defaults to high-speed. This is a fail-safe in case the control wires get cut. An alternate, non-cloned ECU will act like a massive ECU failure, and thus the fan won;t be communicating with it and will kick into high speed.
I still don't believe this is an ECU failure. I think there is an implausible signal for an input to the ECU that causes it to put the fan into "default" mode. Like I said on mine, it was a bad connection at the coolant temperature sensor. With SDS connected, you can go into "Drive" -> "ME 9.7" -> "Actuations" and then select the engine/AC suction fan. In there, you can manually control the fan speed. If this works, then the fan, it's control module, and the ECU are all functioning properly.
05-13-2018, 11:12 AM
#19
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Thread Starter
He didn’t mention any DTC’s he did mention that I was low on Freon.
I beleive when he tried to access the fan with the SDS he wasn’t able to and he said it had to do with an open circuit. I’m going to speak to him tomorrow and get better clarification.
I beleive when he tried to access the fan with the SDS he wasn’t able to and he said it had to do with an open circuit. I’m going to speak to him tomorrow and get better clarification.
05-30-2018, 10:15 AM
#20
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Thread Starter
I finally got the radiator fan working properly!
it turned out to be the ECU. I found a company on eBay that repairs them, I mailed it in and less then a week later it was returned. ($160) but after I installed it and went for a drive I received a check engine light with code P0023 I never had that code before. Any idea what could have caused this
it turned out to be the ECU. I found a company on eBay that repairs them, I mailed it in and less then a week later it was returned. ($160) but after I installed it and went for a drive I received a check engine light with code P0023 I never had that code before. Any idea what could have caused this
06-04-2018, 04:39 PM
#21
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Thread Starter
turns out that the chip that was replaced was damaged after I installed it, they replaced it again and are sending it back to me, but now I’m thinking that its one of three things, 1) they did something wrong when repairing the the ecu, 2) they told me to disconnect the negative cable from the battery before installing the ecu, and I forgot to do that. 3) or I have a short that’s frying the ecu.
can someone provide me with an ecu harness diagram and possibly an explanation on how to test the wires for a short. I have a multimeter reader and light fuse tester. But never had to look for a short before. I want to test the harness before reinstalling the computer again.
can someone provide me with an ecu harness diagram and possibly an explanation on how to test the wires for a short. I have a multimeter reader and light fuse tester. But never had to look for a short before. I want to test the harness before reinstalling the computer again.
07-11-2018, 11:46 PM
#23
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Location: The Woodlands, Texas
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Clk 350
Wow! What a mess man! My radiator fan just went out as well, but mine does not come on AT ALL so when car is idling for about 10 minutes i get a "coolant visit workshop" light. I'm praying i dont have a problem like yours considering i replaced my ECU about 4 months ago, it wouldnt connect to the rear Sam and my car wouldnt start. $1900 later i have my car back but after reading your post its starting to freak me out... hopefully mine is just the fan. Are problems arent quite the same considering my fan doesnt turn on at all, and i agree with ruedney if it was the ECU i doubt your fan would be the only thing wrong.. ill find out next week when i have the time to put my new fan in, I hope all works out for you and you dont end up spending a fortune. I would recommend getting a 2nd or 3rd opinion, because i really dont see how it would be your ECU...
07-11-2018, 11:50 PM
#24
MBworld Guru
If the radiator fan is not operating at all, check the fuse. It's #5 in the pre-fuse box, located under the positive jump terminal:
http://benzbits.com/w203/PreFuse.pdf
http://benzbits.com/w203/PreFuse.pdf
07-12-2018, 11:20 AM
#25
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Clk 350
If the radiator fan is not operating at all, check the fuse. It's #5 in the pre-fuse box, located under the positive jump terminal:
http://benzbits.com/w203/PreFuse.pdf
http://benzbits.com/w203/PreFuse.pdf
