Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Rear A/C (only XC90 with three rows of seats)
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.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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