L322 Range Rover System Description and Operation
AIR CONDITIONING
DESCRIPTION AND OPERATION
82-45
NAS and Gulf States have the longest time period with the blower at full speed and Japan the shortest. TestBook/T4
can be used to change the market setting so, in some cases, if a customer complains of the duration the blower runs
at full speed, changing the market setting could resolve the complaint.
When heating is required, blower speed is reduced if the engine is cold and then progressively increased to the
nominal setting as the engine coolant temperature increases from 20 to 50
°
C (68 to 122
°
F).
On the high line system, blower speed is also influenced by the sunlight sensor. At high light levels blower speed will
increase to increase the cooling effect.
When the blower is selected off temperature regulation is no longer possible so the ATC ECU disengages the
compressor, de-energises the auxiliary water pump and closes the coolant valves. Pressing any of the A/C system
switches restores blower operation and activates the required function. If the blower is selected off when the ignition
is switched off, the blower remains off if the ignition is switched on again within 15 minutes. If more than 15 minutes
elapses between the ignition being switched off and back on again, the ATC ECU switches the blower on at speed 1.
If battery voltage is low the ATC ECU reduces blower speed to conserve power. If battery voltage decreases to less
than 12 V, the ATC ECU decreases the blower signal voltage, and thus the voltage to the blower motor, in direct
proportion to the reduction in battery voltage.
Defrost Programme (High Line System Only)
When the defrost programme is selected the ATC ECU:
l
Opens the windscreen distribution flaps and closes the face and footwell flaps
l
Sets the recirculation flaps to the fresh air position
l
Runs the blower at speed 7
l
Activates the A/C compressor
l
Activates the rear window heater
l
Activates the windscreen heater (where fitted).
When the ambient temperature is 10
°
C (50
°
F) and below, the ATC ECU signals the coolant valves to remain open.
When the ambient temperature is more than 10
°
C (50
°
F), the ATC ECU checks the existing heater matrix
temperature and, if necessary, increases the open time of the coolant valves to produce a minimum heater matrix
temperature of 30
°
C (86
°
F).
The defrost programme is cancelled by pressing the defrost switch again, or pressing the automatic, A/C or maximum
A/C switches
Maximum A/C (High Line System Only)
Pressing the maximum A/C switch while the engine is running and the ambient temperature is more than 7
°
C (45
°
F)
provides the maximum cooling possible from the system to cool the passenger compartment down as rapidly as
possible. When maximum A/C is selected the coolant valves are held closed, the A/C compressor is engaged, the
blower speed is set to maximum and the recirculation flaps are set to the recirculation position. After 12 minutes the
recirculation flaps will be set to fresh air for 1 minute then returned to the recirculation position.
The maximum A/C function is cancelled when any of the other A/C system switches are pressed.
Rest Heating (High Line System Only)
When the engine is not running, pressing the maximum A/C switch activates the rest heating function to heat the
passenger compartment with residual heat from the engine. The rest heating function activates provided the following
conditions exist:
l
It is less than 15 minutes since the ignition was selected off
l
Ambient temperature is less than 15
°
C (59
°
F)
l
On the previous ignition cycle engine temperature exceeded 70
°
C (158
°
F)
l
Battery voltage is 11.4 V minimum.
To provide the rest heating function, the ATC ECU activates the auxiliary coolant pump, coolant valves, control flap
and blower. The ATC ECU regulates the temperature (to the driver setting selected before the ignition was switched
off), opens the face level distribution flaps and runs the blower at speed 4.
The rest heating function is cancelled after 15 minutes or when:
l
The maximum A/C switch is pressed again
l
The ignition is selected on
l
Battery voltage decreases to less than 11 V.
