GF83.65-D-0001H Roof Air Conditioning, Function

GF83.65-D-0001H Roof Air Conditioning, Function

- with CODE (H08) High-performance air conditioning

The rear heavy duty automatic air conditioning is a roof air conditioning system and can only be controlled or regulated using the AAC [KLA] control and operating unit's (S98) integrated rear blower control button (+) (S98s2), rear blower control button (-) (S98s3) and rear temperature selection switch (S98s15) controls if it was switched on using the integrated rear air conditioning button (S98s7).
Activation of the rear heavy duty automatic air conditioning system (roof air conditioning) is indicated by the red light emitting diode (LED) lighting up 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 actuation and subsequent regulation of the ventilation is conducted electrically via the blower regulator (A32/3a1), which regulates the blower motor (A32/3m1).
The temperature is regulated electrically via the blend air flap actuator motor (A32/3m2) and the 2nd refrigerant compressor magnetic clutch (A9/7y1), depending on the temperature of the roof air conditioning evaporator, the refrigerant pressure and the set specified temperature.
The rear heavy duty automatic air conditioning can be summarized by the following subfunctions:
- Ventilation for roof air conditioning
- Roof air conditioning refrigeration circuit
- Roof air conditioning temperature control

Ventilation for roof air conditioning
The ventilation system circulates the recirculated air (air circulation) in the vehicle passenger or load compartment.

Ventilation is only provided in air recirculation mode, no fresh air is drawn in.

The rear blower control button (+) and the rear blower control button (-) can be used to regulate the rate of circulation of the recirculated air. Distribution of the recirculated air is conducted using the roof air duct and the swiveling, lockable air vents.

Roof air conditioning refrigeration circuit
The 2nd refrigerant compressor (A9/7) compresses the gaseous refrigerant, which causes it to heat up. Next, the refrigerant vapor is forwarded to the roof air conditioning condenser, where it is cooled down and thus becomes liquid (condensation).
After being cleaned in the roof air conditioning desiccant cartridge, the liquid refrigerant is routed to the roof air conditioning evaporator over the roof air conditioning expansion valve.
The refrigerant evaporates and cools down the recirculated air that is flowing past. The 2nd refrigerant compressor draws in the coolant which has turned gaseous through the collection of heat.

Rear air conditioning temperature control
The required temperature in the vehicle passenger or load compartment is adjusted using the rear temperature selector switch.
Depending upon the required temperature the position of the blend air flap and shutoff flap is adjusted over the blend air flap actuator motor, the 2nd refrigerant compressor is regulated over the 2nd refrigerant compressor magnetic clutch and the flow of refrigerant to the front evaporator is regulated over the roof air conditioning expansion valve. With this the volume of recirculated air, which is routed over the roof air conditioning evaporator, and the quantity of refrigerant, which is routed through the roof air conditioning evaporator, are regulated to match the temperature of the roof air conditioning evaporator and the refrigerant pressure.