Function
The auxiliary fans (M4m1, M4m2) are switched on in relationship to the refrigerant pressure and/or coolant temperature.
The pushbutton control module receives the refrigerant temperature signal from the air conditioning coolant temperature sensor and the refrigerant pressure from the refrigerant pressure sensor.
This input information is compared with stored values by the pushbutton control module. The calculated output information controls the relay for the auxiliary fans, which switches on the auxiliary fans either directly or over the auxiliary fan preresistor (R15).
The following switching points are possible:
It is not possible to switch on the auxiliary fans in stage 1 at outdoor temperatures <+5 °C.
Auxiliary fan switching points | Stage 1 | Stage 2 |
Refrigerant pressure bar | 16 ON 13 OFF | 20 ON 17 OFF |
A/C coolant temperature sensor, °C vehicles with diesel engine | 107 ON 100 OFF | 115 ON 107 OFF |
A/C coolant temperature sensor, °C vehicles with gasoline engine | 100 ON 95 OFF | 115 ON 107 OFF |
Auxiliary fan control (M4m1, M4m2) V | 9 | 12 |