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Old 09-03-2011, 05:57 PM
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bluebee bluebee is offline
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Location: San Jose, California
Join Date: Mar 2008
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Mein Auto: 02 BMW 525i M54 auto 130K
For the cross-linked record, today, JimLev provided nice aux fan test info:
- E39 (1997 - 2003) > Aux Fan Help

Originally Posted by JimLev View Post
The fan is controlled by the dual temp switch on the side of the radiator and the HVAC system.
Stage 1 is low speed from the HVAC panel or the 91 deg switch on the radiator and relay K21.
Stage 2 is controlled by the AC high pressure switch and relay K22.
Stage 3 (high) is controlled by the 104 C deg switch on the side of the radiator and relay K201, which gets power from fuse F75 (50 amp) behind the glove box. F20 and F105 powers K201.

You said the fan comes on when you turn the AC on so Stage 1 (low) is working which means the 2 resistors are good.
Pull the connector off the dual temp switch and jump it to see if you can get.
Jumping pins 1 to 2 should make it run at high speed and pins 1 to 3 for low speed.
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