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Trying to diagnose a problem I am having with a radiator fan. I did some searching on here and the only thing I could find is that the fan will stay on if the freon is low to save the compressor from overheating with low fluid. I checked the freon level and it is at 70 psi. It seemed high to me but I also unplugged the sensor from the freon in hopes of tricking the system. Does anyone know if I can jumper a couple of wires to trick the computer into thinking the freon is good? Any other thoughts as to why the fan might be on high all the time?
Trying to diagnose a problem I am having with a radiator fan. I did some searching on here and the only thing I could find is that the fan will stay on if the freon is low to save the compressor from overheating with low fluid. I checked the freon level and it is at 70 psi. It seemed high to me but I also unplugged the sensor from the freon in hopes of tricking the system. Does anyone know if I can jumper a couple of wires to trick the computer into thinking the freon is good? Any other thoughts as to why the fan might be on high all the time?
Low side it usuallyb ween 25-45 and high is 200 to 225. Bring it to a AC place and have them do a "Evacuate and Recharge"
And our cars do have a condenser fan seperate correct? You sure your talking about the Radiator fan?
Radiator fan,... that big propeller thingy right behind the radiator,... defaults to spinning in high mode like a jet turbine engine when it's not getting a signal from the ECU.
Radiator fan,... that big propeller thingy right behind the radiator,... defaults to spinning in high mode like a jet turbine engine when it's not getting a signal from the ECU.
That is exactly what it is doing. The car sounds really loud when just sitting there idling.
Usually folks assume the radiator fan or its control module is busted and they buy a replacement (expensive because radiator fan and control module are only sold together),... only to find out that's not the problem.
There's no signal from ECU so radiator fan is spinning in high mode as default,... it assumes the worst and spin in high mode to cool down the engine,.... even though you might have just started car and there's no way its overheating,....
Question is why is there no signal from ECU to radiator fan control module? Could be something as simple as coolant temperature sensor (about $15) needs to be replaced,... could be a fuse or relay,... SEARCH,.... there's a number of threads on radiator fan spinning high.
Also, top up you AC to make sure that's not a factor.
I see this same problem with 2001 to 2005 c240 and c320 models. What happens is the fan will stay on due to a malfunction within the BOSCH ecm, ecu. The most common BOSCH part number to fail is A1121530879 but there are many other part numbers that fail also. Too many to list. If you are having this problem I recommend going to mercedesecm.com and look under the c240 section. Most of the part numbers are listed on this site and so are the prices.
Here are a few other c240 ecm part numbers that have the fan problem
This applies to C240 ML320 E320 and C320 computers there may be others but these are the Mercedes ecu part numbers that fail the most and keep the fan running on high speed. What eventually happens is the fan will burn out and quit working. Part numbers a1121530879 a1121530079 a0245455832 a0245457032 a1121530779 a1121532679 and a1121531279. Hopefully this helps you guys with your mercedes ecm problem. Here is a pic of what the ecu looks like
Does anyone know how the control loop actually works? There are two big wires that control the fan and two small ones that must come from somewhere to govern the speed.
Replace the fan, relay is stock to a high speed and doesnot shift to low
In my case , relay on fan was stock to a high speed . It cAnot be replaced. It is as part of the fan and it is one solid unit . REPLACE THE FAN
Usually folks assume the radiator fan or its control module is busted and they buy a replacement (expensive because radiator fan and control module are only sold together),... only to find out that's not the problem.
There's no signal from ECU so radiator fan is spinning in high mode as default,... it assumes the worst and spin in high mode to cool down the engine,.... even though you might have just started car and there's no way its overheating,....
Question is why is there no signal from ECU to radiator fan control module? Could be something as simple as coolant temperature sensor (about $15) needs to be replaced,... could be a fuse or relay,... SEARCH,.... there's a number of threads on radiator fan spinning high.
Also, top up you AC to make sure that's not a factor.[/QUOTE]
Hi. After my engine has ran for 5-10 seconds my radiator fan comes on and stays on, when the engine stops (stop/start mode) the fan reduces in speed but still runs). Once engine restarts the radiator fan runs at full speed again. If I turn the engine off and back on the fan stays off for a further 5-10 seconds and the kicks in again. I noticed that the aircon was not cooling so I had a top up, when I got in the car it was very cold but when I went to use it the next day the aircon was not blowing cold again.. Also I have to top up my coolant with approximately 500ml every couple of months (2000 miles) Would this contribute to the problem. Just in case this has any bearing on it, I recently took it for an MOT, whilst adjusting the headlight beam the chap blew a bulb in my headlight (which he replaced). I noticed the problem after this but not sure how long after? I would be grateful for any assistance
Radiator fan,... that big propeller thingy right behind the radiator,... defaults to spinning in high mode like a jet turbine engine when it's not getting a signal from the ECU.
I have the same problem and my mechanic says the ECU is shot and that the fan has a constant signal to stay on and that they jumped the temp sender and it is not the problem. From what I have read this doesn't really add up to me...your thoughts? The check coolant display is on and so is the BAS indicator
Trying to diagnose a problem I am having with a radiator fan. I did some searching on here and the only thing I could find is that the fan will stay on if the freon is low to save the compressor from overheating with low fluid. I checked the freon level and it is at 70 psi. It seemed high to me but I also unplugged the sensor from the freon in hopes of tricking the system. Does anyone know if I can jumper a couple of wires to trick the computer into thinking the freon is good? Any other thoughts as to why the fan might be on high all the time?
Does your compressor turn on? does it blow cold if it turns on?
Morning,
I got a 2014 E200 AMG sport ( not an AMG engine) from which had a minor accident at the front, I have replaced all the heating and cooling system but not refilled the AC yet. When i start the car , the radiator fan kicks in like 20-30 seconds and at a very high speed and stays like that through the duration of the car running. I ran my Icar MBII on it and only picked up the P00072 error which is the premair sensor. at the moment mine is loosely attached to the crash bar but i suspect its not its right location as its suppose to be on the front bumper from my research on the internet, can someone please tell me the exact location on an AMG bumper
The other bit am curious about is the Temperature sensor that attaches to the radiator , i notice mine was damaged but because of lack of knowledge i thought it was just the shell that broke not knowing there is a probe that actually goes into the radiator which mine clearly doesn't have. So i know i need to change it, my question is could this be the reason why the rad fan is unusually spinning high, since its a temperature sensor so i suspect because its not sending the temp of the rad to the ECU hence the ECU is sending wrong msg to the fan to spin faster to keep the car cooler. The temperature gauge in the car is normal. I have booked in the car for a specialist to look but just wanted to run this through here to see if my suspicions are right. There are no other issues on the car apart from the ones i have mentioned
Cheers
MS
Last edited by Mark Olasamson; 11-27-2018 at 03:24 AM.
1999 C280 W202 FAN RUNS CONSTANTLY WHEN ENGINE STARTED
HI. MY FAN RUNS ALL THE TIME..FIRST I GET PO118 CODE
THEN FAULT CODES ON MY CCM DISPLAYS
O1 OPEN
03 OPEN
05 OPEN
06 222
07 OPEN
08 OPEN
09 129
10 495
21 240
22 050
23 050
24 13.7
40 03
41 03
42 26
43 6-C
50 77F
51 LO
52 50F
54 OFF
CCM INFO
DL A
226
228
230
232
233
416
422
CAN ANYBODY HELP ME? THESE ARE ALL MY SENSORS IT LOOKS LIKE.
I WANT TO AVOID TAKING IT IN TO THE SHOP,FOR I'M ON S.S.I. AND COULD DO IT MYSELF.(MAYBE)
I USED TO GET 26-30mpg NOW I GET 18mpg IF I'M LUCKY..
THANK YOU FOR YOUR REPLY
Last edited by vinces99c280; 05-08-2019 at 12:36 AM.
Reason: PAGE LAYOUT
HI. MY FAN RUNS ALL THE TIME..FIRST I GET PO118 CODE
THEN FAULT CODES ON MY CCM DISPLAYS
CAN ANYBODY HELP ME? THESE ARE ALL MY SENSORS IT LOOKS LIKE.
I WANT TO AVOID TAKING IT IN TO THE SHOP,FOR I'M ON S.S.I. AND COULD DO IT MYSELF.(MAYBE)
I USED TO GET 26-30mpg NOW I GET 18mpg IF I'M LUCKY..
THANK YOU FOR YOUR REPLY
2) *If* it was a W203, it sounds like the front "SAM" might be bad.
However, I have *no* clue on any other MB platform.
3) Also, please enter at least the country in your profile. There are some important differences, for some models, depending on the country.
4) STOP THE YELLING.
WE HEAR YOU.
PLUS, IT'S VERY HARD TO READ.
MOST OF THE LANGUAGES IN THE WORLD USE LOWER-CASE AND CAPITAL LETTERS FOR VERY GOOD REASONS.
No problem!
Also, start a new thread.
And, you should also post a link to this thread, saying that you did do a search, and did read up on some possible issues.
That way, you don't look like someone that just posts stuff without doing any reading or searching at all.
Hi, I have a w202, when I start my car in the morning, the engine runs and after 20 sec later the radiator fan start to spin at high speed. The last change since this problem appeared, is when I changed the belt for the car. I don't know if this is coincidence when I done the change or it could be a new problem.
I have changed the water sensor that has 2 pins connected to it, as the old one was brittle and it broke.
Another thing is, the idle sits below 1000, and idles at around 5 on the odo, I have to keep it on rev, until the engine is a bit hot and it then sits at about 6 or 7, I would say, but below 1000.
Had the same problem cooling fan always running on S550
Originally Posted by Bradfr
Trying to diagnose a problem I am having with a radiator fan. I did some searching on here and the only thing I could find is that the fan will stay on if the freon is low to save the compressor from overheating with low fluid. I checked the freon level and it is at 70 psi. It seemed high to me but I also unplugged the sensor from the freon in hopes of tricking the system. Does anyone know if I can jumper a couple of wires to trick the computer into thinking the freon is good? Any other thoughts as to why the fan might be on high all the time?
More likely is that the coolant system has not been bled out completely. This causes overheating around the temperature sensor and fans to come on. In this case, no fault codes might get stored.
fill the reservoir all the was up run the heat and rev a bit. Should purge the air out on its own. Worked on mine.
07-15-2012, 01:31 PM
1999 C280 W202 FAN RUNS CONSTANTLY WHEN ENGINE STARTED
