Fan control, function

P07.70-2017-06

A9 Refrigerant compressor

B11/4 Coolant temperature sensor

B40 Oil sensor (oil level, temperature and quality) (up to 05/05)

L5 Crankshaft position sensor

M4/7 Engine and AC electric suction fan with integrated control

N3/10 ME-SFI [ME] control unit

N22 AAC [KLA] control and operating unit

N73 EIS [EZS] control unit

N93 Central Gateway control unit (on model 203 from 04/04 up to 11/04)

CAN-B Data bus design
(Controller Area Network)

CAN-C Engine data bus
(Controller Area Network)

The ME-SFI [ME] control unit indirectly actuates the electric suction fan engine and AC continuously.

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

The duty cycle of the PWM signal is 10 to 90%.

Meaning:

10% Electric suction fan "OFF"

20% Electric suction fan "ON", minimum speed

90% Electric suction fan "ON", maximum speed

The AAC control and operating unit transmits the status of the automatic air conditioning via the CAN data bus to the ME-SFI [ME] control unit. The fan specified speed is dependent on this and on the coolant temperature.

Data exchange between CAN-B and CAN-C takes place via:

 EIS [EZS] control unit except model 203 from 04/2004 up to 11/2004

 Central gateway control unit on model 203 from 04/2004 up to 11/2004

The engine and AC electric suction fan runs on for up to 5 minutes at "Ignition OFF" if the coolant temperature, the engine oil temperature (up to 05/2005) or the temperature of the ME-SFI [ME] control unit exceeds the specified maximum values.

If the battery voltage drops excessively during this operation, engine-off running is suppressed.