i drive 1997 s420 and I have problem with a/c heater blower motor, it continues to run even the car is completely turned off!!!
it happens from time to time, but especially when raining only!
can anybody help me?

bad switch.

Really? Which switch? How could the fan switch be at fault when the thing should be powered off automatically when the ignition is off?

I'm not saying you're wrong, I just don't understand the diagnosis......

Sounds to me like water is getting into something, based on the OP's observation that it happens frequently when raining.

Check and make sure all the drain passages under your hood, etc are not blocked up.

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-tp


1990 300SE "Corinne"- 145k daily driver - street modified differential - PARTING OUT OR SELLING SOON - PORTLAND OR. AREA - PM ME FOR DETAILS
1988 560SEL "Gunther"- 190K passes anything except a gas station
1997 S420 - 265k just bought it with a rebuilt trans. Lovely condition

Is there a switch? I don't know where the OP is, but if he has automatic CC there is no switch. But there is a regulator, and I would suspect it.

Disconnect the Yl wire at the Reg...if motor continues to run, reg is shorted .
Blower is a switched ground circuit , thru the regulator...meaning Red + at blower is ALLWAYS HOT, with Yl being trigger for Regulator .

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A Dalton