SAM Control Module, Refrigerant Compressor

Task
There are two types of input signals for the front SAM:
- Digital signals
- Analog signals

Reading in digital signals.
The signals are read in either shorter or longer intervals depending on how quickly the processor must react to signal changes.

To ensure that the system does not react to short-term interference, the SAM accepts the signal change only if the new value is read in three times in succession.

Reading in analog signals:
The power supply to the switches and sensors depends on the present battery voltage. Before reading in a switch/sensor, the processor first reads the unfiltered battery voltage. If the voltage is within the valid range, the switch can be read in. This voltage is then set in proportion to the switch voltage.To ensure that the system does not react to short-term interference, the SAM accepts changes only if the new value is read in twice in succession. Sensor values are transferred as physical parameters.

The following data is collected by the sensors:
- Refrigerant temperature
The refrigerant temperature sensor is supplied with a voltage of 5V. The sensor ground must be selected jointly for the refrigerant temperature sensor and the refrigerant pressure sensor. The temperature and pressure must also be measured at the same time.
- Refrigerant pressure
The refrigerant pressure sensor is supplied with a stabilized voltage of 5V.The sensor ground must be selected jointly for the refrigerant temperature sensor and the refrigerant pressure sensor. The temperature and pressure must also be measured at the same time.
- Outside temperature
and the following read-in information is made available on the interior bus (CAN B).
- Refrigerant compressor ON
- Refrigerant compressor actuating signal

Actuating the refrigerant compressor
The output of the refrigerant compressor is controlled steplessly. The air conditioning or comfort air conditioning pushbutton control module sends the switch-on request and the desired value (0-100%) to the front SAM via the CAN B to switch on the refrigerant compressor. The current of the refrigerant compressor is controlled (100% corresponds to 1A). At the same time1 the expected torque of the refrigerant compressor is transferred to the engine electronics (ME) and the electronic transmission control (ETC) via the electronic ignition lock control module. The front SAM sends the signal to increase the load to the engine electronic (ME) via the electronic ignition lock control module and switches the refrigerant compressor ON after a defined delay (approx. t = 450 ms).

The air conditioning or comfort air conditioning pushbutton control module sends the switch-off request and the desired value = 0% to the front SAM via the CAN B to switch the refrigerant compressor off.At the same time. the refrigerant compressor torque is set to 0 and transferred to the engine electronics (ME) and electronic transmission control (ETC) via the electronic ignition lock control module. The front SAM sends the deleted load increase signal to the engine electronics (ME) via the electronic ignition lock control module and switches the refrigerant compressor OFF after a defined delay (approx. 450 ms).

If the driver accelerates quickly, the refrigerant compressor is regulated directly by the SAM for a defined time (max. t = 10s), as requested by the engine electronics (ME), to half the value requested by the air conditioning or comfort air conditioning pushbutton control module. The air conditioning or comfort air conditioning pushbutton control module receives the acceleration signal as information.If the engine fan is faulty and if a cooling problem occurs simultaneously (engine temperature too high) the engine electronics (ME) request emergency shutoff of the refrigerant compressor at the air conditioning or comfort air conditioning pushbutton control module or at the front SAM.

Actuating the heater water circulation pump
The heater water circulation pump is actuated by the front signal acquisition and actuation module (SAM) as requested by the pushbutton control module. The front SAM reports the status back to the air conditioning or comfort air conditioning pushbutton control module.The heater water circulation pump is switched on by the air conditioning or comfort air conditioning pushbutton control module under certain operating conditions even if the ignition is switched off. (e.g.residual engine heat utilization).

The heater water circulation pump is switched off by the air conditioning or comfort air conditioning pushbutton control module after t = 30s and after t = 5s.

Measuring the outside temperature
The outside temperature sensor measures the temperature outside the vehicle and passes this value to the front SAM. The front SAM puts this value on the CAN BUS where it can be read in by the air conditioning or comfort air conditioning pushbutton control module and used to control the automatic heater.