<aside> 👋 This is a technical bulletin for the E30 Sanden Conversion Kit. Looking for the full user guide? (learn more)

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Introduction

This technical bulletin covers the basic wiring and modification needed to properly run the high performance SPAL Pusher Fan in place of your original auxiliary fan. Over the years, many BMWs have been repaired, modified, or altered and no longer carry their original equipment so the wiring colors, ballast, and/or overall layout may differ from the instructions below.

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What’s in this technical bulletin?

Installation information

Unlike the factory BMW 2-speed auxiliary fan, the SPAL fan is designed to run on a constant 12v. As a result, the ballast resistor (an electronic component that increases resistance as current increases, and lowers the voltage) will need to be removed from the circuit. The OEM wiring harness features a 3-wire configuration: 12v high-speed signal, 12v low-speed signal, and a ground wire and the fan (OEM or SPAL) uses a 2-wire configuration. In order to maintain the high-speed and low-speed signals from the ECU, you will be required to combine these leads before reaching the fan. Failure to do so will result in no operation of the high-speed or low-speed functionality.

SPAL fan installation

Modifying your existing wiring harness to support the SPAL fan is much easier than it seems and can be done as follows using the instructions and diagrams below:

  1. Disconnect the negative (-) cable from the battery.

  2. Remove the A/C condenser, fan, and resistor on the side of the fan

    Note → You may be required to cut the wiring going to the fan as some models did not come with connectors.

  3. Splice and crimp the OEM ground wire (brown) to the SPAL ground wire (black).

  4. Bridge the high-speed signal (red) and low-speed signal (black) to the SPAL power wire (blue).

  5. Apply heat shrink and check electrical connection.

    Note → Some models come with a 15A fuse for low-speed setting (position #3) on the auxiliary fan. In order to run the SPAL fan, you will be required to upgrade this to a 30A fuse (available here).

  6. Install the A/C condenser and fan.

OEM fan wiring diagram

  1. High-speed signal (+) (red)
  2. Low-speed signal (+) (black)
  3. Ground (-) (brown)
  4. Fan power (+) (red)
  5. Fan ground (-) (brown)

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SPAL fan wiring diagram

  1. High-speed signal (+) (red)
  2. Low-speed signal (+) (black)
  3. Ground (-) (brown)
  4. Fan power (+) (blue)
  5. Fan ground (-) (black)

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Additional diagrams