03 CL55 Coolant Fan Not Coming On
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CL55
03 CL55 Coolant Fan Not Coming On
I recently bought a facelift 55 with a couple of faults (of course 😅
.
The main fault which needs sorting is the suction fan not coming on. I can activate it with a fault code reader, but it won’t come on otherwise.
The previous owner fitted a new rad / fan unit (in an attempt to fix this). The air con system has no pressure (degassed) - which I believe is linked to the suction fan operation.
any advice gratefully received!
.The main fault which needs sorting is the suction fan not coming on. I can activate it with a fault code reader, but it won’t come on otherwise.
The previous owner fitted a new rad / fan unit (in an attempt to fix this). The air con system has no pressure (degassed) - which I believe is linked to the suction fan operation.
any advice gratefully received!
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CL55
…no still not working! This seems to be a common issue with no answers that I can find having trawled the web. I have a theory though, which tomorrow I will try and prove.
I think that the fan is not activating at low speed and thus the engine temperature is rising much higher before it eventually comes on - though I have not let it get this hot. The a/c would normally call the fan on, but mine is not working.
I’m going to test the fan speeds from 10% up with my scanner (which I didn’t do before) and I’ve ordered a portable oscilloscope to see if the ECU generates a signal from when the engine starts (which is when the fan should activate).
I think that the fan is not activating at low speed and thus the engine temperature is rising much higher before it eventually comes on - though I have not let it get this hot. The a/c would normally call the fan on, but mine is not working.
I’m going to test the fan speeds from 10% up with my scanner (which I didn’t do before) and I’ve ordered a portable oscilloscope to see if the ECU generates a signal from when the engine starts (which is when the fan should activate).
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CL55
There is some kind of signal…I think, but the cheapo oscilloscope isn’t very clear - maybe it’s picking up something else? I was able to call the fan in in 10% increments, so it does seem that the fan works. I have ordered a temp sensor, it is cheap but looks really difficult to change on the m113k. Perhaps just connecting the wired to the new sensor and putting it in very hot water will tell me what I need to know. I guess that I will need to earth the body of the sensor.
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Testing isn’t really viable without risking damage to the connector - it’s just to inaccessible. I had my a/c gassed and now the fan works. It works because the a/c calls the fan on - this will do for now.
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Just to wrap this one up, as it might be helpful to someone. I replaced the temperature sensor and now the fan works independently of the air con.
I’ve read a lot of bad advice about how it’s normal for the temperatures on these cars to rise to 100 - it’s not.
I’ve read a lot of bad advice about how it’s normal for the temperatures on these cars to rise to 100 - it’s not.
