Regulation of automatic air conditioning, function

N83.40-2053-02

Shown with code (HZ7) Regulated air conditioning (Tempmatic) in passenger compartment

98/4 Temperature display

98/5 Automatic mode display

98/6 Air distribution duct indicator

98/7 Display of automatic blower preselection stages

98/15 Display

S98 Air conditioning operating module

S98s8 Air distribution switch

S98s9 "AUTO" button

S98s10 Temperature control button

S98s11 Blower control button

The automatic air conditioning (AAC [KLA]) controls the heater, the air conditioning, and the ventilation dependent upon the outside temperature, the temperature in the vehicle interior, the direct solar radiation and the specified temperature value set. The automatic air conditioning control can be switched to automatic mode by pressing the "AUTO" button (S98s9) and back again to manual mode by pressing the button again. If the automatic mode is activated, the automatic mode display (98/5) appears on the display (98/15) of the air conditioning operating module (S98). If the manual mode is activated, the automatic mode display (98/5) goes out on the display (98/15) of the air conditioning operating module (S98).

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If the air distribution switch (S98s8), the temperature control button (S98s10) or the blower control button (S98s11) is operated in automatic mode, the particular air distribution (current position can be seen in the air distribution display (98/6)), temperature control (current temperature can be seen in the temperature display (98/4)) or blower output regulation (current stage can be seen in the display of the automatic blower preselection stages (98/7)) is switched over to manual mode.

The automatic mode display (98/5) remains visible on the display (98/15) of the air conditioning operating module (S98).

The air conditioning operating module (S98) controls the automatic air conditioning, whereby it reads in the integrated buttons and switches as well as the signals of the following components:

 Evaporator temperature sensor (B10/6)

 Refrigerant pressure sensor (B12)

 Outside temperature display temperature sensor (B14), with code (J65) Outside temperature indicator

 Sun sensor (B32)

 In-car temperature sensor (M9b1)

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The air conditioning operating module (S98) also communicates with the following control units via the Controller Area Network bus class B (interior) (CAN-B) and the Controller Area Network Bus Class C (engine compartment) (CAN-C).

 CDI control unit (N3/9), with engine 646

 ME-SFI [ME] control unit (N3/10), with engine 112

 ETC [EGS] control unit (N15/3), with transmission 722.6

 EIS [EZS] control unit (N73)

 Rear AC control unit FONDKLA (N19/3)

The EIS [EZS] control unit (N73) serves as the interface between CAN-B and CAN-C.

The CDI control unit (N3/9), with engine 646, or the ME-SFI [ME] control unit (N3/10), with engine 112, transmits the message "KOMP_BAUS" (switch off refrigerant compressor (A9) due to acceleration) or the message "KOMP_NOTAUS" (emergency shutoff of refrigerant compressor (A9)) to the air conditioning operating module (S98).

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The air conditioning operating module (S98) evaluates the signals and messages and actuates the following components:

 Refrigerant compressor (A9) via refrigerant compressor control valve (A9y1)

 Blower motor (M2) via blower regulator (M2n1)

 Air conditioning additional fan (M4) via switchover relay, refrigeration while driving to stationary refrigeration (K103)

 Blending air flap actuator motor (M16/8)

 Fresh air/air recirculation flap actuator motor (M16/21)

 Air distribution actuator motor (M16/22)

 Coolant circulation pump (M13/5)

 Water valve (Y19/2) via water valve relay (Y19/2k1)

With the message "KOMP_BAUS" (switch off refrigerant compressor (A9) due to acceleration) the air conditioning operating module (S98) uses the refrigerant compressor control valve (A9y1) to reduce the delivery of the refrigerant of the refrigerant compressor (A9) to 40 %.

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With the message "KOMP_NOTAUS" (emergency shutoff of refrigerant compressor (A9)) the air conditioning operating module (S98) uses the refrigerant compressor control valve (A9y1) to reduce the delivery of the refrigerant of the refrigerant compressor (A9) to 2 %.

Moreover, the air conditioning operating module (S98) supplies the control processes as messages for the above listed control units over the CAN-B (e.g., the message "KOMP_EIN", refrigerant compressor (A9) switched on).

The ETC [EGS] control unit (N15/3), with transmission 722.6, reads in the message "KOMP_EIN" (refrigerant compressor (A9) switched on) for example and evaluates it for the correction of the torque.

The CDI control unit (N3/9), with engine 646, or the ME-SFI [ME] control unit (N3/10), with engine 112, reads in the message "KOMP_EIN" (refrigerant compressor (A9) switched on) for example and evaluates it for the idle speed control.