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I have this issue with my W204 C320 CDI, not happening always, but 3/4 times I take the car is overheating when driving through the city, and my dash is showing me IMG-9481.jpg (640×360) (ibb.co)
Temperature gets lower when I drive at higher speeds, likely 50+KM/H. I checked for the fan and when the car begins to overheat is not working, neither if I start the AC (which doesn´t work either), car gets to 100ºC and the fan won´t work at all. When the fan runs normally everything else works normally, including the AC and the fan starting when I turn it ON. Radiator seems to be working fine, coolant level is okay too, it´s just the fan that sometimes works sometimes doesn´t, the relays are looking good, not melted or smth. Took it to a car service and they told me they´re getting a fault on the AC and that probably is the radiator fan, problem is, a new radiator fan is too expensive to change it just on a ¨probably¨ case.
Someone else had this happening and fixed it without changing the fan, or at least fixed it by changing it? Could a partially faulty relay be the cause, as it is intermittent? I´ve been reading on the forum but didn´t find anything conclusive about the W204.
I have this issue with my W204 C320 CDI, not happening always, but 3/4 times I take the car is overheating when driving through the city, and my dash is showing me IMG-9481.jpg (640×360) (ibb.co)
Temperature gets lower when I drive at higher speeds, likely 50+KM/H. I checked for the fan and when the car begins to overheat is not working, neither if I start the AC (which doesn´t work either), car gets to 100ºC and the fan won´t work at all. When the fan runs normally everything else works normally, including the AC and the fan starting when I turn it ON. Radiator seems to be working fine, coolant level is okay too, it´s just the fan that sometimes works sometimes doesn´t, the relays are looking good, not melted or smth. Took it to a car service and they told me they´re getting a fault on the AC and that probably is the radiator fan, problem is, a new radiator fan is too expensive to change it just on a ¨probably¨ case.
Someone else had this happening and fixed it without changing the fan, or at least fixed it by changing it? Could a partially faulty relay be the cause, as it is intermittent? I´ve been reading on the forum but didn´t find anything conclusive about the W204.
Thank you.
You have a lot of issues with temps, A/C and mainly a questionable engine fan that can run by only sometimes... fuse likely ok!
Go ahead and scan the car to gather all available evidence. The scanner will provide a survey of issues that may be related.
When the engine fan circuit fails, it tends to run at full speed. That not being the case you may just be dealing with a sensor circuit issue.
Last edited by CaliBenzDriver; Jul 27, 2023 at 01:51 PM.
You have a lot of issues with temps, A/C and mainly a questionable engine fan that can run by only sometimes... fuse likely ok!
Go ahead and scan the car to gather all available evidence. The scanner will provide a survey of issues that may be related.
When the engine fan circuit fails, it tends to run at full speed. That not being the case you may just be dealing with a sensor circuit issue.
I´ll search for another service to do a more exhaustive scan, I tested the car today and everything worked perfectly, fan working normally and same for the AC, no overheating. On monday I´ll search for another service to check it... I was thinking on the Coolant Temperature Sensor, I´m not sure if it´s controlling the fan in our car, could be? I mainly don´t want to spend a few hundred € just to not fix anything by changing the fan. When it´s working it´s perfectly fine,I turned the AC on and the fan started spinning, at first the speed was normal and then it increased for a few seconds and decreased again, so It´s obvious as you say that the fan engine is okay, I´ll drop the idea of changing it for now. With your last paragraph you mean it could be bad wiring, right? English is not my main language and I´m not sure I understood you completly right, thank you for answering!
Forgot to say, also thinking on the CTS because when the car overheats, if I turn off the engine, when I turn it back on, it shows the temperature to be at 90ºC for maybe 20 or 30 seconds, and then the temperature raises to whatever it´s overheated and I get the coolant warning on my dash.
I want to say the overheating can do terminal damages to your car.... don't drive it ignoring it is sick! In other words don't drive it at all until fixed.
Your fan is almost entirely prooven good. To me this sounds like an ECU GND issue.
I understand you don't have a scanner and to go forward that what you need to help yourself.
Another word of caution, these cars require an MB specialist to diagnose them properly, not a tire shop mechanic that will replace parts after parts without an end in sight.
Buy a scanner or pay a specialist shop - Actually there is a way to rent a scanner + a specialist, remotly... @BenzNinja
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
If you have access to Amazon (and we don't know where in the world you are because you don't show your location), an inexpensive and relatively good Mercedes-specific scanner is the iCarsoft MB V3.0 (not the MB II). Every Mercedes owner should have one and keep it in the car. It's small enough to fit in the glove box.
Got a fan from spare parts and changed it, it´s now fixed so that was it, the fan was faulty.
The symptoms, in case it happens to someone else are: 1: The fan works intermittently, when starting the car for the first time it always works (in the morning), after that it doesn't matter how much you stop it and start it because it seems that the error is stored for a few hours before self-removing. 2: After driving for X time (sometimes more, sometimes less) the AC stops working and the car starts to get hotter when stopping or going slowly, less than 50-60Km/h 3: Sometimes, when the fan stops working it seems that the thermostat is also blocked open, because if I go by highway the temperature starts to drop below 90ºC.It is very easy to detect it since the moment the AC stops working and it starts to heat up, it is simply to open the hood of the car and see if the fan works, anyone can check it with the naked eye.If it doesn't work, you may have the same problem as me.The fix, just change the fan in my case, nothing else, no thermostat or coolant sensor or anything, just the fan. Comment that my old fan on the outside is "like new" and that when it worked normally, the motor was strong and everything seemed correct.
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[FIXED] W204 overheating, fan not always working
