Rear A/C (only XC90 with three rows of seats)

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Fig 1: Rear A/C

Courtesy of VOLVO CARS OF NORTH AMERICA.

XC90 with three rows of seats is equipped with a rear A/C system. This consists of:

power unit
fan
expansion valve
blower fan switch.

The rear A/C system is controlled by a switch in the lower section of the dashboard environment panel. When the switch is activated the climate control unit (CCM) transmits a signal to the rear electronic module (REM) via the Control area network (CAN). The rear electronic module (REM) supplies the power unit and the blower fan switch with voltage via a relay. The blower fan switch sends control voltage to the power unit based on the position of the control. The power unit converts the control voltage to supply voltage for the blower fan motor.

The rear A/C is directly connected to the front air conditioning via the high and low pressure pipes and hoses. The only way to control the cooling in the third row of seats is to control the fan speed using the rear fan switch.

The rear electronic module (REM) diagnoses the relay supply, otherwise the rear A/C cannot be diagnosed.