The regulator is a switching device, voltage controlled, that switchs the ground at the blower motor on and off continuously, so that fan speed is determined by on duty cycle. You will need a duty cycle meter or oscilliscope to check it.

However, if you do NOT have power at the output side of the strip fuse, you have a wiring problem. Must have 12V on both sides.

If the blower runs with 12 V applied and proper ground, your problem is in the control circuit. This could be bad wiring (do you have 12V at the plug to the motor?) or the regulator gone south (expensive).

Also, make sure you don't have something in the heater box locking the fan cages up -- this will blow the fuse.

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!