I have a 1998 C230 with the non-supercharged motor. A/C blows warm, compressor does not kick on. The auxiliary fan never comes on, regardless if I'm using the air conditioning or not. The engine temperature stays right around 80 Celsius unless I sit in traffic, in which case it will head up towards 100 and the auxiliary fan does not come on.

Haven't found any bad fuses or relays, the connection to the fan is in good shape. The a/c system is full of r-134a. I'm tempted to just replace the fan, but I don't have much diagnostic information on this vehicle so I don't want to jump to a conclusion.