Radiator fan always on HIGH, regardless of weather or a/c, this is not normal.
09-20-2020, 11:21 PM
#51
Island
I have this same problem for nearly 6 years now, I have a W202 1999 C200 automatic. First happened after the car was stood still for a long while after battery died. Then the electronic ignition switch had failed, replaced it for another one coded by MB in Germany to my keys.
Then after the coolant/washer low fluid light would come on automatically from turning the car on. With the engine fan running at high speed. At times it may cut off, but then it would come back on after about 2 mins and stay on permanently for around 20 mins or more.
I went through countless parts to try and fix the problem - with no success. Parts bought virtually all brand new from MB.
Coolant low level sensor
Windscreen washer fluid sensor
Engine thermostat
Engine coolant temperature sensor
AC engine compressor (this ended up failing about 2 years ago)
Engine cooling fan
Engine Cooling fan module (mounted under front nearside wheelarch inner panel)
Just been reading another thread and they said a float is inside the coolant expansion tank, so may just go and check that out to see if its dislodged.
I even used Star DAS connected to my laptop, but it does not give anything specific to the problem. I then even cleared all faults, but still same thing.
I had import the car abroad 10 years ago, I have had nothing but problems, mainly electrical, if I had known they would be like this I would NEVER have bought this car, and went for aother model or manufacturer.
To make matters worse there is no MB dealer on the island. I have worked on many vehicles and clued up about cars, but this one is weird.
Then after the coolant/washer low fluid light would come on automatically from turning the car on. With the engine fan running at high speed. At times it may cut off, but then it would come back on after about 2 mins and stay on permanently for around 20 mins or more.
I went through countless parts to try and fix the problem - with no success. Parts bought virtually all brand new from MB.
Coolant low level sensor
Windscreen washer fluid sensor
Engine thermostat
Engine coolant temperature sensor
AC engine compressor (this ended up failing about 2 years ago)
Engine cooling fan
Engine Cooling fan module (mounted under front nearside wheelarch inner panel)
Just been reading another thread and they said a float is inside the coolant expansion tank, so may just go and check that out to see if its dislodged.
I even used Star DAS connected to my laptop, but it does not give anything specific to the problem. I then even cleared all faults, but still same thing.
I had import the car abroad 10 years ago, I have had nothing but problems, mainly electrical, if I had known they would be like this I would NEVER have bought this car, and went for aother model or manufacturer.
To make matters worse there is no MB dealer on the island. I have worked on many vehicles and clued up about cars, but this one is weird.
what island ?
09-25-2020, 01:07 AM
#52
HI Friends,
I have a 2010 model E class W212 200CGI. Yesterday when I started the car, it started normal, but after 30 seconds, the radiator fan starts running in full speed. Also noticed the climate control unit is fully dead. I checked the fuse #12 and seems good. Also I tried disconnecting battery for some time and started the car, but still same issue persists. One suggestion came is a/c pressure switch could be bad. Any help is highly appreciated from you Merc experts..
Thanks
Lalmon
I have a 2010 model E class W212 200CGI. Yesterday when I started the car, it started normal, but after 30 seconds, the radiator fan starts running in full speed. Also noticed the climate control unit is fully dead. I checked the fuse #12 and seems good. Also I tried disconnecting battery for some time and started the car, but still same issue persists. One suggestion came is a/c pressure switch could be bad. Any help is highly appreciated from you Merc experts..
Thanks
Lalmon
Last edited by lalmon; 09-29-2020 at 02:49 AM.
09-28-2020, 07:19 AM
#53
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w204 200 cdi
Hi
I have a w204 200cdi, recently changed water pump and thermostat housing with radiator coolant, all done by Mercedes dealership with OEM parts. Problem is that fan switches on the free way at 120 km/hr, Coolant temperature from the ECU is 79-83 degrees celcius. A/C is switched off. Fan is constantly on. Drove the car for an hour, fan never switched off. Temperature gauge on the car dropped justed below the 80 degree mark and then slowly went to 90 degrees. My car is still ar the dealership. Any ideas?
TIA
I have a w204 200cdi, recently changed water pump and thermostat housing with radiator coolant, all done by Mercedes dealership with OEM parts. Problem is that fan switches on the free way at 120 km/hr, Coolant temperature from the ECU is 79-83 degrees celcius. A/C is switched off. Fan is constantly on. Drove the car for an hour, fan never switched off. Temperature gauge on the car dropped justed below the 80 degree mark and then slowly went to 90 degrees. My car is still ar the dealership. Any ideas?
TIA
03-08-2021, 01:35 AM
#54
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E350 cdi
Did you find the cause of this issue please?
my fan waits for a couple of hours then does exactly this.
Thanks
my fan waits for a couple of hours then does exactly this.
Thanks
Need help.
The fan on my c350 2010 starts up a couple of hours after my car has stopped and it sounds like a jet engine, there's no key in the ignition and the fan ramps up and the ramps back down. This happened on Friday and it eventually run the battery down. I sent it to the Mercedes specialist and he said there were no fault codes and couldn't find a problem with it. Got it back yesterday and drove it Monday for an hour and couple of hours at stand still and it's started up again.
Took it back and he thought it may be the fan and controller. Had this changed along with the battery and again tonight the fan has started running yet.
I'm stumped and would love to know what the problem is and what I can do about it please.
The fan on my c350 2010 starts up a couple of hours after my car has stopped and it sounds like a jet engine, there's no key in the ignition and the fan ramps up and the ramps back down. This happened on Friday and it eventually run the battery down. I sent it to the Mercedes specialist and he said there were no fault codes and couldn't find a problem with it. Got it back yesterday and drove it Monday for an hour and couple of hours at stand still and it's started up again.
Took it back and he thought it may be the fan and controller. Had this changed along with the battery and again tonight the fan has started running yet.
I'm stumped and would love to know what the problem is and what I can do about it please.
04-03-2021, 03:37 PM
#55
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S211
Hello I am new to this forum so I am not sure if I am posting this in the right place? I would appreciate some help if possible?
I have an S204 2008 with a fan constantly running problem. The AC does not work. My Autel diagnostics tells me the AC pressure is too have 3000 bar.
I have measured the voltage at the AC pressure sensor and with the cable removed from the sensor I read 4,88 volts on both the signal and supply wires. Somehow the signal wire is getting 5V somewhere other than the sensor? The voltages are present when the car is switched off. They only go to zero when the car is locked.
I have inspected the fan module and looked at the PWM signal on the scope. This looks OK. I am not sure what the second red/black wire is for?
The fan switches off when the engine is switched off.
Can anyone help with this? Russell Ormerod seems to have plenty of knowledge in this area.
Many thanks
I have an S204 2008 with a fan constantly running problem. The AC does not work. My Autel diagnostics tells me the AC pressure is too have 3000 bar.
I have measured the voltage at the AC pressure sensor and with the cable removed from the sensor I read 4,88 volts on both the signal and supply wires. Somehow the signal wire is getting 5V somewhere other than the sensor? The voltages are present when the car is switched off. They only go to zero when the car is locked.
I have inspected the fan module and looked at the PWM signal on the scope. This looks OK. I am not sure what the second red/black wire is for?
The fan switches off when the engine is switched off.
Can anyone help with this? Russell Ormerod seems to have plenty of knowledge in this area.
Many thanks
03-08-2023, 04:45 AM
#56
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E Class W212
There are a bunch of causes to having a fan turn on high regardless of temp. Some more information regarding your vehicles cooling system would help. Do you have a viscous engine fan and aux. electric fans or just the electric cooling/engine fan? Even a pic of your engine bay would help.
I had a similar problem, my problem started with a dealership change of my climate control head unit. My car is a 2000 C280 with an electric cooling/engine fan only. When I would start my car the fan would come on and stay on high until the car was shut down regardless of temp. The dealership told me this was normal so I believed them for 3 years! Finally I researched and found out that the climate control head unit needs to be version coded correctly in order to operate the cooling system in your vehicle properly. There is a document that explains how to do this which I can forward you if you feel it is your situation.
I had a similar problem, my problem started with a dealership change of my climate control head unit. My car is a 2000 C280 with an electric cooling/engine fan only. When I would start my car the fan would come on and stay on high until the car was shut down regardless of temp. The dealership told me this was normal so I believed them for 3 years! Finally I researched and found out that the climate control head unit needs to be version coded correctly in order to operate the cooling system in your vehicle properly. There is a document that explains how to do this which I can forward you if you feel it is your situation.
I have a new unit on order, and hopefully, that will solve the fan issues. I have matched the part numbers like for like, so hopefully it will be coded fine, but fully expect to have to code it myself or take it to a garage.
03-08-2023, 05:07 AM
#57
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E Class W212
HI Friends,
I have a 2010 model E class W212 200CGI. Yesterday when I started the car, it started normal, but after 30 seconds, the radiator fan starts running in full speed. Also noticed the climate control unit is fully dead. I checked the fuse #12 and seems good. Also I tried disconnecting battery for some time and started the car, but still same issue persists. One suggestion came is a/c pressure switch could be bad. Any help is highly appreciated from you Merc experts..
Thanks
Lalmon
I have a 2010 model E class W212 200CGI. Yesterday when I started the car, it started normal, but after 30 seconds, the radiator fan starts running in full speed. Also noticed the climate control unit is fully dead. I checked the fuse #12 and seems good. Also I tried disconnecting battery for some time and started the car, but still same issue persists. One suggestion came is a/c pressure switch could be bad. Any help is highly appreciated from you Merc experts..
Thanks
Lalmon
I have presumed it was the control unit as it died a slow death - buttons stopped working etc, so I have a new one arriving tomorrow.
03-09-2023, 01:11 AM
#58
There are a bunch of causes to having a fan turn on high regardless of temp. Some more information regarding your vehicles cooling system would help. Do you have a viscous engine fan and aux. electric fans or just the electric cooling/engine fan? Even a pic of your engine bay would help.
I had a similar problem, my problem started with a dealership change of my climate control head unit. My car is a 2000 C280 with an electric cooling/engine fan only. When I would start my car the fan would come on and stay on high until the car was shut down regardless of temp. The dealership told me this was normal so I believed them for 3 years! Finally I researched and found out that the climate control head unit needs to be version coded correctly in order to operate the cooling system in your vehicle properly. There is a document that explains how to do this which I can forward you if you feel it is your situation.
I had a similar problem, my problem started with a dealership change of my climate control head unit. My car is a 2000 C280 with an electric cooling/engine fan only. When I would start my car the fan would come on and stay on high until the car was shut down regardless of temp. The dealership told me this was normal so I believed them for 3 years! Finally I researched and found out that the climate control head unit needs to be version coded correctly in order to operate the cooling system in your vehicle properly. There is a document that explains how to do this which I can forward you if you feel it is your situation.
If you have any info that you could share, I would be greatly appreciative.
By the way a couple days ago. I cranked up the car and the fan doesn't come on at all. Thinking maybe the fan finally got tired and just DIED. .
Any info is again appreciated. Thank you 😊
Last edited by Justice Devine; 03-09-2023 at 01:18 AM.
03-09-2023, 09:26 AM
#60
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E Class W212
This a quick update for future forum users who may have the same issues, base on the posts I made in this thread.
• Climate Control Unite (Thermotronic Dual Zone) died a slow death on my W212.
• First the row of buttons would only work pressed upwards, then a few days later, the whole unit died.
• After it died, the check engine light came on.
• After that, when I was driving, the engine fan would blow full blast.
Unsure why or how the engine fan and climate control are linked, but they are it seems. I changed the unit for a second-hand one off eBay, £35. I made sure all the serial numbers on the back matched the ones on the ebay one. It was from a coupe, mine's a saloon, so the outer casing was different, but a few screws and you can get the PCB out of the unit and put it in your existing unit. Helps if the one you are buying is a scratched-up mess as well.
After that, the unit turned on, the heaters blow, and the fan on the engine stopped blowing. The engine light stayed on, but I have just driven it a few hours later and the light has gone off.
A word of warning, though – be careful putting the screws back in the dash. I dropped one, no idea where it's gone behind the dashboard. I hope it doesn't get in the way of anything or rattle around.
• Climate Control Unite (Thermotronic Dual Zone) died a slow death on my W212.
• First the row of buttons would only work pressed upwards, then a few days later, the whole unit died.
• After it died, the check engine light came on.
• After that, when I was driving, the engine fan would blow full blast.
Unsure why or how the engine fan and climate control are linked, but they are it seems. I changed the unit for a second-hand one off eBay, £35. I made sure all the serial numbers on the back matched the ones on the ebay one. It was from a coupe, mine's a saloon, so the outer casing was different, but a few screws and you can get the PCB out of the unit and put it in your existing unit. Helps if the one you are buying is a scratched-up mess as well.
After that, the unit turned on, the heaters blow, and the fan on the engine stopped blowing. The engine light stayed on, but I have just driven it a few hours later and the light has gone off.
A word of warning, though – be careful putting the screws back in the dash. I dropped one, no idea where it's gone behind the dashboard. I hope it doesn't get in the way of anything or rattle around.
