Hello, can anyone help me out, I need to troubleshoot my cooling system, my main fan and aux fan do not come on. I have try to short out the thermo switch and nothing, I tested one of the wire from the thermo switch to the relay and it ohmed out. I noticed that the relay always stays hot or active no matter what the temp is, I just read a post about ac, and tomorrow I am going to try shorting out the pressure switch on the ac drier to see if that will work make the fans come on, what i need is a good reference on how to test each compoment in the cooling system and ac, to eliminate what the reason that both fans are not comming on. I will also try to hot wire the aux. fan and ohm out the magnetics of the main fan , anybody have any wirediagrams to this system, also my ac doesn't seem to be comming on when i push the switch to engage it. I have a climate controll problem, but i will troubleshoot that at later time, probably a vac problem with the climet control. one more thing, i have this wire that someone added to a sensor plug next to the thermo switch that runs back to a black box on the fuel distribution housing. any help on what and where that wire is going and what it is intended for, and is there any way to directly make the main fan to operate beside shorting out the thermo switch, even thow there is power at the relay and its being engage. well thanks for any help you can provide.[8D]

 

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Have you tried unplugging the fan & running 12V (thru a fuse) to it to see if it works? there's a seperate fuse for that fan on my 560SL. Ck the fuses.