<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 options

The factory BMW auxiliary fan operates at 2 speeds via a low and high-speed 12v signal from the ECU that runs through a ballast resistor (an electronic component that increases resistance as current increases, and lowers the voltage). The OEM wiring harness features a 3-wire configuration: 12v high-speed signal, 12v low-speed signal, and a ground wire while the fan (OEM or SPAL) uses a 2-wire configuration (power and ground).

There are 2 primary ways to install the SPAL fan:

  1. Option A - Maintain the factory 2 speed functionality (recommended)
  2. Option B - Run the fan on high at all times (this will result in the highest possible airflow, but will also have an increase in fan noise)

SPAL fan installation (Option A)

Modify the SPAL fan wiring harness to support a 2 speed fan operation using the instructions 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. Connect the SPAL power wire (blue) to the high-speed pole (red) on the ballast resistor.

  5. Apply heat shrink and check electrical connection.

    Note → For the E30, some models came 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.