if your defrost fan is showing some signs of life get it on life support asap.it may just require some bearing lubrication.i beleive you can get at it for lubrication purposes by removing the chrome intake vent below the windshield.even with that removed you will probably have to use some kind of flexible tube to aim the oil precisely upon the bearings.the alternative to this is RandR.not a fun job considering the console and heater core/evaporator must be removed to get at it

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michael cole 1980 300SD gone now but not forgotten,87tdt,90 300te 4matic 95 e320 wagon