If the strip fuse is okay, check the high speed fans by pulling the coolant temp sensor connector off with the engine running and observing the fans go to high.

If they check okay, then check the low speed fans. With the car at idle and the air on, the fans should usually cycle on and off every minute or so, as the coolant temp bounces between approximately past 85-95C (it doesn't sound like yours are doing this). If they don't cycle, check the low speed relay by turning the ignition on and, with a paper clip, jumping the two pig tail connectors that go into the a/c receiver (jump the connectors--not the sensor on the receiver side). If you hear a click when you jump it, the relay works. If the relay works, you could be low on freon. There is also a possibility that the big low speed fan resistor behind the front left headlight is bad, or the terminals/wires are corroded.

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles