GF83.57-D-2030H Roof Air Conditioning Temperature Control, Function
GF83.57-D-2030H Roof Air Conditioning Temperature Control, Function
- with CODE (H08) High-performance air conditioning
S98 AAC [KLA] control and operating unit
S98s2 Rear blower control button (+)
S98s3 Rear blower control button (-)
S98s7 Rear air conditioning button
S98s15 Rear temperature selection switch
The temperature of the rear heavy duty automatic air conditioning (roof air conditioning) can only be regulated by the AAC [KLA] control and operating unit's integrated rear temperature selection switch when it is switched on using the integrated rear air conditioning button. Activation of the heavy duty rear automatic air conditioning is indicated by illumination of the red light emitting diode (LED) in the rear air conditioning button.
The rear heavy duty automatic air conditioning can be used to provide a comfortable interior climate for the vehicle occupants in the vehicle passenger or load compartment in different weather conditions.
The rear temperature selection switch is used to set the required temperature in the vehicle passenger or load compartment and it is regulated to match the temperature of the roof air conditioning evaporator and the refrigerant pressure.
Turning the rear temperature selection switch to the left reduces the temperature in the vehicle passenger or load compartment.
Turning the rear temperature selection switch to the right increases the temperature in the vehicle passenger or load compartment. The AAC [KLA] control and operating unit reads in the values of the following components:
- Evaporator temperature sensor (A32/3b1)
- Blend air flap potentiometer (A32/3r2)
- Roof refrigerant pressure sensor (B12/6)
The KLA control and operating unit reads in the 3 values and regulates the 2nd refrigerant compressor (A9/7) via the 2nd refrigerant compressor magnetic clutch (A9/7y1) and the blend air flap actuator motor (A32/3m2) depending on the specified temperature set via the rear temperature selection switch.
The blend air flap actuator motor adjusts the blend air flap and shutoff flap thus regulating the air flow of the recirculated air, which flows over the roof air conditioning evaporator.
Actuation of the 2nd refrigerant compressor via the 2nd refrigerant compressor magnetic clutch is mainly dependent on the value of the evaporator temperature sensor, because the refrigerant pressure in the heavy duty rear automatic air conditioning changes depending on the required cooling in the roof air conditioning evaporator and the 2nd refrigerant compressor must interrupt or continue the refrigerant delivery via the 2nd refrigerant compressor magnetic clutch.
It is not possible to heat the recirculated air using the rear temperature selection switch.
To speed up the increase or reduction in temperature the AAC [KLA] control and operating unit's integrated rear blower control button (+) and the rear blower control button (-) can be used to adjust the output of the blower motor (A32/3m1) in 3 stages.
Distribution of the recirculated air is conducted using the roof air duct and the swiveling, lockable air vents.
Actuation of the 2nd refrigerant compressor via the 2nd refrigerant compressor magnetic clutch is simultaneously placed as message "KOMP_EIN" (2nd refrigerant compressor switched on) on the Controller Area Network bus Class B (interior) (CAN-B). The EZS control unit (N73) reads in the message "KOMP_EIN" (2nd refrigerant compressor switched on) and places it on the Controller Area Network bus Class C (engine compartment) (CAN-C). The "KOMP_EIN" (2nd refrigerant compressor switched on) message is read in by the CDI control unit (N3/21), with engine 646, by the CDI control unit (N3/20), with engine 642, by the ME control unit (N3/29), with engine 271, or by the ME control unit (N3/23), with engine 272, and used for the idle speed control. At the same time, the "KOMP_EIN" message (2nd refrigerant compressor switched on) is read in by the EGS control unit (N15/3), with transmission 722.6, and used to correct the torque.
Inversely, the CDI control unit, with engine 646 or with engine 642, or the ME control unit, with engine 271 or with engine 272, transmits the message "KOMP_BAUS" (Switch off 2nd refrigerant compressor because of acceleration) or the message "KOMP_NOTAUS" (Emergency shutoff of 2nd refrigerant compressor) to the EZS control unit via the CAN-C.
The KLA control and operating unit reads in the message "KOMP_BAUS" (Switch off 2nd refrigerant compressor because of acceleration) or the message "KOMP_NOTAUS" (Emergency shutoff of 2nd refrigerant compressor) from the EZS control unit via the CAN-B and switches off the refrigerant delivery of the 2nd refrigerant compressor via the 2nd refrigerant compressor magnetic clutch.
