92 500sl Aux Fan problem(s)

[bdelmonico]

I asked this question 9 years ago and I still have not figured it out yet Here is the question: Aux fans come on when the air comes on they do not come on w/o the air. I thought that is how it was designed....wrong What I understand is that they should come on stage 1 when the coolant temp gets to 105C or 220F? If they still do not come on w/o air what can I check to get them working properly? I know there is relay and I know there is a ballast resistor where are these located and how do you test them and what else could it be? is there an error code for that?

[Diseasel300]

If your cooling system is operating properly, you shouldn't be seeing the Aux fan coming on at all if the A/C is not in use. Your coolant temps should never be getting above 100˚C anyway, the engine driven fan should be keeping temps in check. If you're having overheating problems when the A/C is not in use (no aux fan), the fan clutch should be a prime suspect.