IHKA E36 Auxiliary Fan Control
The auxiliary fan can be turned on by:
- A request from the IHKA control panel/module (normal speed operation).
- High refrigerant pressure (high-speed operation).
- High coolant temperature (normal or high-speed operation).
6- and 4-cylinder engines have different circuits. On 6-cylinder engines, the IHKA control panel/module circuit used to request A/C compressor operation is also used to energize the auxiliary fan normal speed relay. On 4-cylinder engines, the engine control module grounds the relay.
On 6-cylinder engines, the coolant temperature switch activates the normal speed relay. On 4-cylinder engines, the coolant temperature switch signals the engine control module that the coolant is too hot, and the engine control module activates the relay.