Hi all, I recently bought a 2005 C180 Kompressor. Ive noticed that the radiator fan runs at high speed when vehicle is started in the morning. Its now winter is SA. Some mornings it runs at startup, some mornings not.

Currently the AC compressor is faulty and needs to be replaced, the AC gas is also under pressured as it was not re gassed by the company testing the AC compressor.
I have rad many threads about this complex issue and I am aware the radiator fan get some commands from the AC pressure and other systems.
These new AC compressors are hellish expensive in SA, so for now, we are not going to use the AC function, however logic tells me that we need to at least re gas the AC system.

I have however noticed that the fan does not seem to engage when temp reaches 80 Degrees on the temp gauge. The temp has also gone up to about 90 degree mark, still the fan does not engage.
Fan was tested with diagnostic machine and it does run when receiving commands from software.

So any thoughts on this and mostly at what temp on the temp gauge should the fan start running ?

 

The M271 engine (ie your car engine) is designed to run at 90C. Internally, a thermostat opens the pipe to the radiator at 90C. If you're not going above that (e.g. 100C), you're fine.

The fan running during startup probably has to do with the AC system as you say. I'd ignore it until you have the AC compressor replaced and the system recharged.

 

Don't know the starting temp of the fan from my Mercedes, but on my Ford it is 118F. If you have a faulty AC system, it is a safety feature to turn the fan on.