BenzWorld Junior Member
Date registered: Nov 2007
Vehicle: 1998 ML320 & 1999 E430
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E430 AC Auxiliary Fan Not coming on...
I have a 1999 e430 which has lost power to its twin Auxiliary AC Fans. The fans are suppose to come on automatically when the AC is on, but no longer do. The AC does still work, but barely in recent 100 Houston temperatures without the fans working.
I know it is not the fans themselves in that they will come on if hot-wired from the battery with a probe intersecting the lead in wire at the point of connection to the fans. (btw, warning. Don't try permanently doing this by tying the wire into the headlights. It will either blow the fuse, or start smoking)
From my research, the obvious culprit should be the Auxillary Fan Control Unit, a finned box that mounts under the drivers side headlight. I bought and installed a new unit, but that didn't change the problem. There does not appear to be any other fuses or relays involved in the system according to several mechanics I have spoken with. The wires appear fine.
I suppose there is an off chance that the new AFCU I bought was faulty, but am not yet ready spring another couple of hundred for another one until all else is ruled out.
Any ideas and /or a link to an AC wiring diagram or schematic would be appreciated.