Fan control - function - GF07.61-P-3023BK

ENGINE 113.967 in MODEL 219

ENGINE 113.964 in MODEL 164.1

ENGINE 113.971 in MODEL 251

Fig 1: Fan Control Function Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The ME control unit indirectly actuates the "electric suction fan engine and AC with integrated control" continuously.

The fan specified speed is transmitted by the ME control unit via a pulse width modulated signal (PWM signal).

The on/off ratio is 10 to 90%.

Meaning:

10% Electric suction fan "OFF"

20% Electric suction fan "ON", minimum rotational speed

90 % Electric suction fan "ON", maximum rotational speed

If the actuation is faulty, the electric suction fan rotates with maximum rotational speed (fan emergency mode).

The status of the automatic air conditioning unit is transmitted via the CAN data bus by the AAC [KLA] control and operating unit, via the central gateway control unit to the motor electronics control unit. The fan specified speed is dependent on this and on the coolant temperature.

The suction fan continues running for up to 5 minutes after ignition "OFF" if the coolant temperature, the engine oil temperature (from the temperature model) or the temperature of the ME control unit exceeds specified maximum values.

If the battery voltage drops excessively during this operation, suction fan run-on is suppressed.

If an SBC undervoltage occurs, the fan speed is limited and a fault is stored in the fault memory (model 219).

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