Replace the strip fuse -- it's in a little box close to the fuse box.

The strip fuse (very much like the fuse for the glow plugs but lighter) cracks with age and use, so it will conduct enough to show voltage at no load, but not enough to actually deliver any current. Your VOM will show voltage, but if you hook up a test lamp, it will be dim.

Costs about $.50.

If that doesn't fix it, it's likely the motor controller in the AC box (to the rear of the blower) or the pushbutton control unit.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!