You said that it was snowing. Do you have the heater on full blast? I have found that my car (an 85 300sd) will not charge when the heater blower motor is running full blast. Of course I suspect my battery and alternater need to be replaced, but that blower motor draws quite a bit of current when opperating at full blast.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

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