Relay is probably stuck, but I don't know which one it is off the top of my head. Easy way to check is to start pulling the small ones in the fuse box. When the fan quits, you have the correct relay!

Is it high or low speed? High speed is the engine temp sensor, low speed is the pressure switch on the AC receiver/dryer -- check that the wires aren't shorted.

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!