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Home >> Jaguar >> 2012 >> XJ Base >> Repair and Diagnosis (Single Page) >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Climate Control -- XJ/X351 >> Climate Control >> Description And Operation >> Control Components - System Operation And Component Description (G1772639) >> Principles Of Operation >> Programmed Defrost
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Programmed Defrost

The programmed defrost DEF switch is located on the ICP. When the switch is pressed, the ATCM instigates the programmed defrost function. When selected, the ATCM configures the system as follows:

The ATCM also sends a medium speed MS CAN body systems bus message to the Central Junction Box (CJB) to activate the windshield heater (where fitted) and rear window heater.

On vehicles fitted with the four zone system, the rear climate control panel shows a defrost symbol to indicate that the system is in defrost and no air flow will be available to the rear vents.

The programmed defrost function can be cancelled by one of the following:

The blower speed can be adjusted without terminating the programmed defrost function. If the blower speed has been adjusted and then the DEF switch is pressed again, the system will go back to the DEFROST default settings. Another press of the DEF switch, or pressing the driver AUTO switch, will exit the DEFROST mode but leave the heated screen(s) on.