HVAC Occupant Climate Control (Auto A/C) – Description and Operation Page 2D-1
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Section 2D
HVAC Occupant Climate Control (Auto A/C) –
Description and Operation
ATTENTION
Before performing any service operation or other procedure described in this Section, refer to Section 00
Warnings, Cautions and Notes for correct workshop practices with regard to safety and / or property damage.
1 General Information ...............................................................................................................................3
2 General Description ...............................................................................................................................4
2.1 OCC Control Module.............................................................................................................................................. 5
OCC Input Data ...................................................................................................................................................... 5
OCC Output Data ................................................................................................................................................... 6
OCC Control Module configuration...................................................................................................................... 6
OCC Control Module components ....................................................................................................................... 7
2.2 Multi-function Display ........................................................................................................................................... 8
2.3 Rear Remote Control............................................................................................................................................. 9
Rear Remote Control Components.................................................................................................................... 10
3 OCC System Sensors ..........................................................................................................................11
3.1 In-car Temperature Sensor ................................................................................................................................. 12
Aspirator Tube and Venturi................................................................................................................................. 12
3.2 Evaporator Temperature Sensor........................................................................................................................ 13
Evaporator Temperature Control........................................................................................................................ 13
3.3 Ambient Temperature Sensor............................................................................................................................. 14
3.4 Sun Load Sensor ................................................................................................................................................. 15
4 System Operation.................................................................................................................................16
4.1 Overview............................................................................................................................................................... 16
Recommended Settings...................................................................................................................................... 16
Dual Zone Operation............................................................................................................................................ 16
Link Mode......................................................................................................................................................... 16
Unlink Mode ..................................................................................................................................................... 16
Mode Control.................................................................................................................................................... 16
Fan Speed Control........................................................................................................................................... 16
Blower Fan Control.............................................................................................................................................. 16
Automatic Mode ............................................................................................................................................... 16
Air Distribution Control....................................................................................................................................... 17
Automatic Mode ............................................................................................................................................... 17
Air Inlet Control.................................................................................................................................................... 18
Automatic Mode ............................................................................................................................................... 18
Vent Air Temperature Control............................................................................................................................. 18
Manual Mode ................................................................................................................................................... 18
Automatic Mode ............................................................................................................................................... 18
OCC Cold Start-up Routines............................................................................................................................... 19
Default Mode: Vacuum Leak............................................................................................................................... 19
Automatic Operation ........................................................................................................................................... 19
4.2 OCC System Activation....................................................................................................................................... 21
4.3 HVAC Unit Airflow Modes ................................................................................................................................... 23
HVAC Unit and Airflow Diagram......................................................................................................................... 23
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Recirculation Mode.............................................................................................................................................. 24
Full Cold........................................................................................................................................................... 24
Full Heat........................................................................................................................................................... 25
Face Mode ............................................................................................................................................................ 26
Full Cold........................................................................................................................................................... 26
Full Heat........................................................................................................................................................... 26
Bi-level Mode........................................................................................................................................................ 27
Full Cold........................................................................................................................................................... 27
Full Heat........................................................................................................................................................... 27
Floor Mode............................................................................................................................................................ 28
Full Cold........................................................................................................................................................... 28
Full Heat........................................................................................................................................................... 28
Blend Mode........................................................................................................................................................... 29
Full Cold........................................................................................................................................................... 29
Full Heat........................................................................................................................................................... 29
Demist Mode......................................................................................................................................................... 30
Full Heat and A/C Activated ............................................................................................................................. 30
Default Mode ........................................................................................................................................................ 31
Loss of Vacuum Supply to HVAC Unit ............................................................................................................. 31
5 Specifications.......................................................................................................................................32
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1 General Information
This Section provides a gener al description of the operation of the electronic control components of the occupant climat e
control system. For the general descr iption of the operation of the heater and air-conditioner system, except the
electronic control system refer to Section 2A HVAC Climate Control (Manual A/C) – Description and Operation
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2 General Description
The occupant climate control (OCC) system uses the following compon ents to control the operation of the heater a nd air-
conditioning system:
• push button occupant climate c ontrol (OCC) control module,
• in-car temperature sensor,
• sun load sensor,
• ambient temperature sensor,
• evaporative temperature sensor,
• vacuum solenoid pack,
• water valve vacuum switching valve, and
• air mix door motor.
The OCC system can maintain a preset level of cooling or heating regardless of inside or outside temperature
fluctuations. The electronic sensors listed above al low the system to respond to various changes in ambient temperature,
evaporator temperature, interior cabin temperature and sun load.
The OCC system has the capabilit y to use recirculated air in conjunction with all other ventilation mode s. The OCC
system will adjust automatically to any climate and temperature chang es to maintain the vehicle cabin interior within the
selected temperature range. This is achieved by automaticall y controlling:
• heater water valve opening and closing,
• air mix door movement,
• fresh/recirculation door positio n,
• blower fan speeds, and
• ventilation mode selection.
Air-conditioner compressor cycling is controlled by the engine control module (ECM) for V6 engine or the powertrain
control module (PCM) for GEN III V8 engine, in accordance with the pressure signal sent to it by the air-conditioner
pressure transducer and serial data communication with the body control module (BCM). Engine cooling/condenser fan
operation is controlled by the ECM (V6) or the PCM (GEN III V8).
A rear remote control, which allo ws rear passengers to control the temperature, fan speed and som e op erational modes
of the OCC system is also fitted. The rear remote control also incl udes certain audio cont rols and is located in the centre
of the headlining, forward of the rear passenger seating area. Refer to 2.3 Rear Remote Control for further information.
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2.1 OCC Control Module
The OCC control module (1) is located bel ow the face level centre vents (2) and is attached to the back of the instrument
panel centre fascia (3) assembly, refer to Figure 2D – 1. Contained within t he OCC control module is all software
required to control the OCC system in c onjunction with the body control modu le (BCM) and the engine control module
(ECM) for V6 engine or the powertrain control module (PCM) for GEN III V8 engine,.
Figure 2D – 1
The OCC control module oper ates the desired HVAC functions, operating modes and ca bin temperature. Included in its
functions are switches for windscreen demisting mode and the heated rear window. LED switch illumination is provided
when the windscreen demister and he ated rear window are activated. All wording and ico ns on the buttons are
illuminated when the park lamps are activated. Their illumination level is adjusted by the same means and to the same
level as the instrumentation illumination.
The OCC control module incorporates a microprocessor to monitor inputs, process data and thus control outputs.
OCC Input Data
• Priority key user and ignition off time from the BCM.
• Engine RPM.
• Coolant temperature.
• Road speed.
• A/C pressure from the ECM (V6) or the PCM (GEN III V8).
• Sun load sensor.
• In-car temperature sensor.
• Ambient temperature sensor.
• Evaporative temperature sensor.
• Air mix potentiometer.
• Ignition Voltage.
• Blower Fan Voltage.
• Occupant settings by way of the OCC buttons.
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OCC Output Data
• A/C request to the ECM (V6) or the PCM (GEN III V8).
• Air Distribution Mode (by controlli ng the logic of the vacuum solenoi ds):
• Demist,
• Foot,
• Foot and face (bi-level),
• Face.
• Vent air temperature by controlling the position of the air mix doors between approximately 5°C with A/C on and
approximately 70°C with a warm engine.
• Air Inlet Mode (fresh or recirculated) by controlling a vacuu m solenoid.
• Water valve operation by controlling the water valve vacuum switching valve.
• Blower fan speed by an analogue signal sent to the electronic blower motor controller, which amplifies this signal
and thus controls the blo wer voltage.
• Maximum blower relay.
• Rear window demist relay.
• Multi-function display.
The OCC control module’s active functions and ventilation settings are d isplayed on the upper p ortio n of the
multi-function display (MFD) sc reen. An outside temperature reading is also displayed in th e MFD. Refer to
2.2 Multi-function Display for further information.
OCC Control Module configuration
The OCC control module includes the push buttons for the operator to control the OCC system, refer to Figure 2D – 2.
The driver's set temperature button (4) is on the right-hand side and the front passenger's temperature switch (2) is on
the left-hand side. T wo R markings (1) on the mounti ng flanges indicate the module is for right-ha nd drive applications.
Figure 2D – 2
Legend
1 R Indication for Right-hand drive Application
2 Passenger Side Set Temperature Switch
3 Blower Fan Speed Switch
4 Driver Side Set Temperature Switch
5 Windscreen Demist Mode Switch and LED Indicator
6 OCC System Off Switch
7 OCC System Automatic Operation Switch
8 Air-conditioning On / Off Switch
9 Ventilation Mode Selection Switch
10 Fresh / Recirculation Mode Selection Switch
11 Heated Rear Window Switch and LED Indicator
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OCC Control Module components
The OCC control module is attached to the rear of the instrument panel centre trim and is retained by four screws.
The ten control buttons clip into, and are retained by, the front module housing which clips over and locks to the rear
housing at eight locations.
Contained within the module are two printed circuit boards. Information from the front circuit board is transferred to the
rear circuit board through a ribbon cable. A 16-pin and a 20-pi n electrical connector protrude through ape r tures of the
module’s rear housing.
The module has no serviceable components. If any component fails the modul e must be replaced.
Figure 2D – 3
Legend
1 Rear Module Housing
2 Rear Circuit Board
3 X1 Connector
4 X2 Connector
5 Ribbon Cable
6 Front Circuit Board
7 Silicone Switches
8 Lower Switch Housings
9 Front Module Housing
10 Upper Switch Relay Pins
11 Upper Switch Fascias
12 Lower Switch Fascias
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2.2 Multi-function Display
The OCC control module’s active functions and ventilation settings are displayed on the upper portion of the Multi-
function Display (MFD). This includes an outside temperature function, which is displayed whenever the ignition is on.
The MFD is also used to displa y current time and audio system settings. These are displayed on the lower portion of the
MFD screen.
The MFD (1) is located above the face level centre vents (2) and is attached to the back of the instrume nt panel centre
trim assembly (3), refer to Figure 2D – 4.
For further information of the MFD refer to Section 12I Multi-function Displ ay.
Figure 2D – 4
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2.3 Rear Remote Control
Rear seat passengers have access a rear remote control (1), which is fitted to the centre of the headlining (2), forward of
the rear passenger compartm ent.
Figure 2D – 5
The rear remote control combines a number of entertainment system functions with the following OCC system functions:
• temperature up or down, and
• fan speed up or down.
Pressing any one of these s wit ches will turn the system on and control the appropriate function. Pressing the fan Up and
fan Down switches simultaneously for less th an two seconds will switch the OCC system to AUTO mode. The fan speed,
temperature setting and vent settings will then be controlled automaticall y.
Each switch has a unique resistance value. The OCC control module uses this val ue to determine which switch has been
pressed and alters the HVAC settings accord ingly. The OCC system cannot be turned off at the rear remote control.
Figure 2D – 6
Legend
1 Next Track / Station Back Switch
2 Next Track / Station Forward Switch
3 Volume Down Switch
4 Volume Up Switch
5 Mode Switch – AM / FM Radio, CD Player or DVD Player
6 Temperature Down Switch
7 Temperature Up Switch
8 Blower Fan Speed Down Switch
9 Blower Fan Speed Up Switch
10 Front Fascia / Housing
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Rear Remote Control Components
The rear remote control housi ng forms the front fascia and sides of the unit. Nine switches (five audio and four OCC
system) are held in location by the same three scre ws used to assemble the circuit board, the illum ination plate and foam
piece to the housing. A single, six termin al e lectrical connector is bonded to the top of the circuit board and protrudes
through an aperture in the metallic rear cover. The rear cover is attached to the housing by four screws.
The complete unit is attached to the headlining by two integral hooks, formed as part of the top of the rear cover, and two
screws installed to the underside of the front housing. These screws can be accessed by removing the two plastic cover
plugs used to conceal them.
The three bulbs used to provide illumination can be servic ed when the complete unit has been remove d from the
headlining and the rear cover is detached, refer to Section 12B Lighting System. No other item of the unit is serviced. If a
component fails, excluding the illumination b ulbs, the comp lete unit must be replaced.
Figure 2D – 7
Legend
1 Rear Cover Screws
2 Rear Cover
3 Bulbs
4 Internal Screws
5 Wiring Connector
6 Circuit Board
7 Illumination Plate
8 Foam Piece
9 OCC System Switches
10 Entertainment System Switches
11 Front Fascia / Housing
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3 OCC System Sensors
Figure 2D – 8
Legend
1 Sun Load Sensor
2 In-car Temperature Sensor 3 Ambient Temperature Sensor
4 Evaporative Temperature Sensor
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3.1 In-car Temperature Sensor
The in-car temperature sensor is a negative temperature co- efficient (NTC) thermistor used to monitor the vehicle’s
interior air temperature. Resistance signals are constantly m onitored by the OCC control module and are used for
subsequent control of the OCC system.
It is essential the venturi and aspirator tube assembly be properly connected to the in-car temperature sensor if the
sensor is to provide correct information to the OCC control module, refer to Aspirator Tube and Venturi in this Sectio n for
further information.
The in-car temperature sensor (1) is located on the right-
hand side of the steering column (2) behind the air holes (3)
on the instrument cluster trim assembly.
Figure 2D – 9
Aspirator Tube and Venturi
The aspirator tube is a formed plastic tube that is installed between the in-car temperature sensor and a venturi located
on the top of the HVAC case. When the blower fan is operating, positive air pressure is forced through the venturi. This
causes air to be drawn from the vehicle inter ior throu gh the in-car temperature sensor to the venturi via the aspirator
tube. The inducted air is used to aid the in-car temperature sensor to react quickly to any temperature changes taking
place within the vehicle int erior.
The aspirator tube (1) is located on th e top o f the HVAC
case (2). The front section of the tube is retained to the cas e
by a locating lug (3). Two retainin g clips (4) moulded to the
case retain the centre section of the tube.
The rear of the tube is fitted into the induction port of the
venturi (5) The base of the venturi (inlet port) is installed to
the venturi air hole (6) located in the evaporator cover of the
HVAC case.
Figure 2D – 10
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3.2 Evaporator Temperature Sensor
The evaporator temperature sensor is a negative temperature co-efficient (NTC) thermistor used to monitor the
temperature of the air into the HVAC unit after it has passed through the evaporator. Resistance values are constantly
monitored by the OCC control module and a r e used for subsequent control of the OCC system.
The evaporator temperature sensor (1) is located on
evaporator (2) by a plastic retaining clip (3). The installation
point of the sensor to the evaporator is critical for correct
OCC system performance. Refer to Section 2F HVAC
Occupant Climate Control (Aut o A/C) – Removal and
Installation for the specified installation dimensions.
Figure 2D – 11
Evaporator Temperature Control
As the air-conditioning system uses a varia bl e stroke compressor, the evaporator temperature sens or is only used to
sense A/C temperature for the OCC software calculations, not to cycle the compressor on or off. Anti ice-up is governed
by the evaporator pressure control valve loca ted within the compressor.
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3.3 Ambient Temperature Sensor
The ambient temperature sen sor (1) is installed on a bracket
(2) that is permanently attached to the front of the air-
conditioning condenser (3) on the lower right-hand side.
It is a negative temperature co-efficient (NTC) thermistor
used to monitor the ambient (outside) temperature. This
sensor is slow reacting due to the dens e plastic housing
surrounding it.
The OCC takes into account road speed before updating the
temperature display to avoid false readings in heavy traffic
or extended idle conditions.
Figure 2D – 12
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3.4 Sun Load Sensor
The sun load sensor (1) is incorporated into the remote
receiver module and is located in the ce ntre of the demist
grilles. For the purposes of the OCC system, it is used to
monitor the sun’s heating load upon the veh icle.
It is a photochemical type sensor, meaning that a small
electrical current will be gener ated, which depends on the
sun load (strength) over it. When the sun’s intensity is high,
the OCC control module will select a higher blower fan
speed and increased veh icle cooling automatically.
Likewise, when the sun load is low, such as going into an
underground car park, the OCC control module will
automatically reduce the fan speeds and inc rease heating
slightly.
Signals are sent from the sun load sensor directly to the
BCM then to the OCC control module via the serial data line
input.
Figure 2D – 13
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4 System Operation
4.1 Overview
Recommended Settings
The customer should be encouraged to operate the OCC system in full Auto Mode (orange Auto LED on) and a set
temperature of 23°C.
Changing the Set temperature to suit different conditions could cause the OCC to behave differently from what the
customer expects (eg. setting to 17°C on a hot day could cause the customer to complain the blower speed is too hi gh
on hot days). This should be discouraged.
Dual Zone Operation
Link Mode
The link mode refers to the mode when the operation of both the passenger and dr iver air mix motors are synchronised.
When the driver ‘set’ temperat ure is changed, likewise the passenger ‘set’ temperature changes to the same value. To
access the link mode, press and hold the AUT O button for more than two seconds.
Unlink Mode
This mode is when the passenger sets their desired temperature independent of the driver. To access Unlink Mode,
press the passenger side temperatur e button.
NOTE
If the OCC was previously operating in Link
Mode, this action will switch the system to Unlink
Mode.
Mode Control
It is not possible for the passenger to alter the mode positions such as Floor, Demist, and Centre Vent etc. There is no
individual control, mode p ositi ons will be the same for both passenger and driver.
Fan Speed Control
As with the mode control, it is not possible for the passenger to alter the blower fan speeds as an individual function.
Once the blower speeds have bee n selected, blower speeds for both the passeng er and driver will be the same.
Blower Fan Control
There are step-less blo wer fan speeds available in the Automatic Mode and five speeds in the Manual Mode. Manual fifth
speed is the same as highest automatic blower fan speed.
To improve battery life, when the engi ne is not running the actual blower speed will not be higher than fan speed 3.
Automatic Mode
The blower fan speed will vary according to:
• in-car temperature,
• ambient temperature,
• sun load,
• manually selected set temper ature,
• coolant temperature, and
• air distribution mode.
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If the cabin is at the required temperature, the blower speed will be at a minimum. An increase in sun l oad in these
conditions would cause the blower speed to increase. If heating of the cabi n is required (eg. after a cold night), the
blower would gradu ally increase as the coolant temperature increased to a pproximately 70°C. Then, as the in-car
temperature increased, the blower would decrease.
If extreme cooling of the cabin were required, the blower would increase to maximum speed (over about 15 seconds).
Then, as the in-car temperature decreased, the blower would also decrease. If cooling of the cabin is req uire d, an
increase in sun load will cause the blower speed to increase. If heating of the cabin is requir ed, an increase in sun load
will normally cause the blower speed to decrease.
If the air distribution mode changes, (eg. from Face to Face / Floor) the fan speed may also change. In order to maintain
a constant airflow, the blower voltage is compensated for:
• road speed,
• air inlet Mode, and / or
• ignition voltage.
Air Distribution Control
There are 5 distribution Modes that can be selecte d eith er automatically or manually. These are:
• Demist,
• Blend (foot / demist),
• Foot,
• Bi-level (foot / face), and
• Face.
Automatic Mode
The air distribution mode sele cted will vary according to:
• in-car temperature,
• ambient temperature,
• sun load,
• manually selected set temperature, and
• start up conditions.
If the cabin is at the desired temperature, the OCC will select either Foot / Face or Face Mode (depending if the cabi n
needed to be warmed or cooled).
If cooling of the cabin were required, Foot Mode may be selected for a short time (A/C purge), followed by Face Mode.
If heating of the cabin is required, Demist Mode would be selected until the coolant is warm enough (demist delay),
followed by Foot / Demist. Then, as the In-car temperature increased, the Mode should change to Foot / Face.
If heating is required and the coolant is warm, Foot Mode may be selected for a short time (purge), followed by
Foot / Face Mode (or Foot / Demist Mode depending on conditions).
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Air Inlet Control
When Recirculate is selected either manually or automatically, the OCC will return the air inlet to Fr esh Air Mode after
approximately 40 minutes. This is to avoid stuffiness in the car. The customer can return to recirculate by pressing the
Recirculate button.
Automatic Mode
The air inlet Mode selected will vary according to:
• in-car temperature,
• ambient temperature,
• sun load,
• manually selected set temper ature,
• start up conditions,
• evaporator temperature,
• A/C pressure, and
• coolant temperature.
If the cabin does not require cooling or A/C is off, fresh air will be selected.
If extreme cooling of the cabin were required, fresh air may be selected for a short time (fresh de lay), then Recirculation
Mode will be selected until the cabin has cooled sufficiently. Then, Fresh Air Mode will be selected.
If the cabin requires cooling, air mix is at full cold, the evapo rator temperature is high and the A/C pressure is high,
Recirculation Mode may be selected (e.g. heavy traffic on a hot day). T hen, as the in-car temperature decreases to a
suitable level, Fresh Air Mode will be selected.
If the coolant temperature gets very high, Recirculation Mode ma y be selected to increase the cooling capacity of the
radiator.
Vent Air Temperature Control
The vent temperature will vary between approximately 5°C (with A/C on and air mix door at minimum) and approximately
70°C (with 90°C coolant and air mix door at maximum).
Manual Mode
When the set temperature is scrolled lower than 17°C or higher than 30°C, the OCC s ystem changes to manual mode
with full uncontrolled cooling or full uncontrolled heating respectively.
If the Set temperature is set to C, the air mix door will be set to minimum.
If the Set temperature is set to H, the air mix door will be set to maximum.
Automatic Mode
When a Set temperature of between 17°C and 30°C is selected, the vent air temper ature will be controlled automatically.
The vent air temperature will vary according to:
• in-car temperature,
• ambient temperature,
• sun load, and
• set temperature.
When the cabin is at the desired temperature, the average vent air tempera t ure should be approximatel y the same as th e
set temperature.
If the cabin requires cooling, the OCC control module will control the vent temperature to less than the set temperature.
The more cooling required, the lower the vent temperature should be.
If the cabin requires heating, the OCC control module will control the vent temperature to be more than the set
temperature. The more coolin g required, the higher the vent temperature shou ld be.
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Generally, the automatic blower will be at a fairly low level (l ess than 50%) before the OCC control module starts to
control the temperature. For example, when extreme cooling is required, the blower will st art on maximum and the air
mix will start at minimum. As the cabin cools down the blower will decrease gradually, while the air mix will stay at
minimum, then, when the blower is appro ximately 40%, the air mix door maybe ope ned to turn the water valve on. Then
as the cabin keeps cooling down, the blower is gradually decreased as the vent temperature is increased.
• Increasing the set temperature will increase the vent temperature (provided air mix is not at maximum).
• Decreasing the set temperature will decrease the vent temperature (provided air mix is no t at minimum).
• As the in-car temperature increases the vent temperatur e will decrease.
• As the in-car temperature decreases the vent temperature will increase.
• As the sun load increases the vent temperature will decrease.
• As the sun load decreases the vent temperature will increase.
• As the ambient temperature increases the vent temperature will decrease.
• As the ambient temperature decreases the vent temperature will increase.
The OCC control module controls the air mix position to achieve the req uired vent temperature, compens ating for:
• evaporator temperature,
• coolant temperature,
• inlet mode, and
• air distribution mode.
OCC Cold Start-up Routines
There are four cold start-up routines incorporated in the OCC system logic to cater for various conditions on first starting
the vehicle, typically at low ambient temperatures.
Each routine has its own respective criteria to satisfy before the routine is executed:
• Recirculation delay: Automatically defaults to recirculation mode to prevent cold air from entering the vehicle
interior.
• Demist delay: To eliminate cold air at floor durin g warm-up and prevents the driver’s breath from fogging front
windscreen.
• Purge: Allows coolant to heat the heater core and avoid humidity to face / windscreen when the blower fan is
activated.
• A/C Purge: To avoid hot air blowing on face when the blower fan is activated.
• Fresh delay: Uses cooler outside a ir to purge hot air from the vehicle.
Default Mode: Vacuum Leak
When a leak is apparent in the vacuum system, the air direction will automatically default to demist and fresh air. Refe r to
Default Mode for further information.
Automatic Operation
In Automatic Mode, the microprocessor uses the sunlight, in-car temperature, ambient temperatur e, evaporator
temperature and Set temperature to deci de and control the amount of blower voltage and the air inlet mode.
The Auto button contains an Orange LED that when:
• ON: indicates the OCC system is in full Auto mode (all functions are controlled automatically).
• OFF: indicates the OCC system is in part Manual mode (at least one function is not b eing controlled automatically).
Any of the Auto functions can be manually o verridden by pressing the appropriate button.
NOTE
If one function has been se lected manually, other
functions still operate automaticall y.
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The OCC control module uses the in-car temperature sens or, the ambient temperature sensor, the sun load inp ut from
the body control module (BCM) and the set temperature to determine if the cabi n temperature requires warming, cooli ng
or maintaining. The following tables provide examples of what the OCC system will attempt under various conditions:
The OCC will try to maintain the cabin temp in the following situations:
The OCC control module will t ry to maintain the cabin temp in the following situations:
Set Temp In-Car Temp Ambient Temp Sun Load Typical Situation
23°C 25°C 23°C Low Driving for a while on a warm night
23°C 27°C 12°C Low Driving for a while on a cold night
23°C 23°C 23°C Medium Driving for a while on a spring afternoon
The OCC control module will cool the cabin in the following situations:
Set Temp In-Car Temp Ambient Temp Sun Load Typical Situation
23°C 40°C 23°C Low Dusk, car has been sitting in the sun
23°C 23°C 23°C High Been driving for a while in early afternoon sun
23°C 23°C 30°C Low Been driving for a while on a h ot night
23°C 55°C 30°C High Car has been sitting in sun on a hot summer’s
day. Extreme cooling is required
17°C 23°C 23°C Low Driver wants to cool down quickly
The OCC control module will heat the cabin in the following situations:
Set Temp In-Car Temp Ambient Temp Sun Load Typical Situation
23°C 15°C 15°C Medium Morning drive after a cool night
23°C 20°C 20°C Low Early morning drive after a mild night
23°C 23°C 10°C Low Been driving for a while on a cold night
23°C 5°C 5°C Low Morning drive after a cold night
Extreme heating is required
30°C 25°C 20°C Low Driver wants to warm up quickly
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4.2 OCC System Activation
The following table provides a summary of button functions:
Button Function
Set Temperature Button
Allows cabin temperature sele ction between 17° and 30°C.
T = Set temperature decrease
S = Set temperature increase
Will turn the OCC system on when selected.
Outside 17° to 30°C range, the OCC system changes to
manual mode.
Blower fan
Manual operation – 5 speed
Automatic operation – step-less
T = speed decrease
S = speed increase
Will turn the OCC system on when selected.
Rear Window Demist
Provides rear window heatin g. Orange LED illuminates
when activated.
Will not turn on the OCC system when selected.
Recirculation
Prevents outside air entering the vehicle cabin when
activated. Function can be selected whether OCC system
is on or off when ignition is on.
Will not turn on the OCC system when selected.
Air Distribution
When selected the OCC system will scroll through F ace,
Bi-level, Floor or Blend mode settings.
Will turn the OCC system on when selected.
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Button Function
Air-conditioning
Turns A/C system on or off.
Will turn the OCC system on when selected.
Automatic Operation
The OCC system will operate in the Automatic Mode,
controlling the blower fan speed, air distribution, air inlet
function and air outlet temperature automatically.
Will turn the OCC system on when selected.
OCC System Off
Will turn the OCC system on or off when selected.
Windscreen Demist
Directs air to the windscreen. Orange LED illuminates
when activated.
Will turn the OCC system on when selected.
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4.3 HVAC Unit Airflow Modes
HVAC Unit and Airflow Diagram
The HVAC unit has seven different possible modes:
• recirculation,
• face,
• bi-level,
• floor,
• blend,
• demist, and
• default.
The following airflow mode diagrams provide a schematic representation of ho w cold and heated air flows through the
HVAC unit during the seven different possible modes. Each schematic has a graphic representation of the OCC control
module matching the given m ode.
When the set temperature is scrolled lower than 17°C or higher than 30°C, the OCC s ystem changes to manual mode
with full uncontrolled cooling or full uncontrolled heating respectively, for the driver and front passenger sides with
switch (4) and the front passenger side only with switch (5). Refer to Figure 2D – 14.
Figure 2D – 14
Legend
1 HVAC Unit
2 Airflow Schematic
3 OCC Control Module
4 Set Temperature Switch – Driver's Side
5 Set Temperature Switch – Front Passenger's Side
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Recirculation Mode
Full Cold
The fan switch (1) is used to select any one of five speeds, refer to Figure 2D – 15. The side T of the MIN MAX switch
(2) has been selected resulting in full, uncontrolled coolin g. The mode control switch (3) is set to face mode. The A/C
switch (4) is on and the recirculation switch (5) has also been selected. All of these settings are displayed on the multi-
function display (6).
NOTE
Recirculation mode can be selected
independently of all other air distribution modes
excluding dem ist mode.
The plenum chamber (outside air) inlet (7) to the HVAC unit is closed off by the recirculation door (8). Interior air (9) is
drawn into the HVAC unit through the recircu lation inlets (10) by the blower motor fan (11), and is then forced through the
cold evaporator fins (12). In full cold mode the air mix doors (13) are positioned to allow all air to bypass the heater
core (14). The cold air travels through the open face door (15) and is then directed out (16) of the HVAC unit to the
centre and side vents.
Figure 2D – 15
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Full Heat
The fan switch (1) is used to select any one of five speeds, refer to Figure 2D – 16. The side S of the MIN MAX switch
(2) has been selected resulting in full, uncontrolled heatin g. The mode control switch (3) has been switched to face
mode. The recirculation s witch (4) has been selected. All of these settings are displayed on the multi-func tion display (5).
NOTE
Recirculation mode can be selected
independently of all other air distribution modes
excluding dem ist mode.
The plenum chamber (outside air) inlet (6) to the HVAC unit is closed off by the recirculation door (7). Interior air (8) is
drawn into the HVAC unit through the recircu lation inlets (9) by the blower motor fan (10), and is then forced through the
evaporator fins (11). In full heat mode, the air mix doors (12) will be positioned so that all incomi ng air is directed through
the heater core (13). The air travels throug h the open face door (14). The heated air (15) is then directed out through the
centre and side vents.
Figure 2D – 16
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Face Mode
Full Cold
The fan switch (1) is used to select any one of five speeds, refer to Figure 2D – 17. The side T of the MIN MAX switch
(2) has been selected resulting in full, uncontrolled coolin g. The mode control s witch (3) has been switched to face mode
and the A/C switch (4) is on. All of these settings are displayed on the multi - function display (5).
The recirculation door (6) are closed allowing outside air (7) to enter and flow into the HVAC unit via the plenum chamber
inlet (8). Air is drawn into the HVAC unit by the blower motor (9), and is then forced through the cold evaporator fins (10).
In full cold mode, the air mix doors (11) are positioned to allow all air to bypass the heater core (12). The air travels
through the open face door (13). The cold air (14) is then directed through the centre and side vents.
Figure 2D – 17
Full Heat
The fan switch (1) is used to select any one of five speeds, refer to Figure 2D – 18. The side S of the MIN MAX switch
(2) has been selected resulting in full, uncontrolled heatin g. The mode control switch (3) has been switched to face
mode. All of these settings are displayed on the multi-function display (4).
The recirculation door (5) are closed allowing outside air (6) to enter and flo w into the HVAC unit via the plenum chamber
inlet (7). Air is drawn into the HVAC unit by the blower motor (8). This air is then forced through the evaporator core
fins (9). In full heat mode, the air mix doors (10) will be positioned so that all incoming air is directed through the heater
core (11). The air travels through the open face door (12). The heated air (13) is then directed out through the centre and
side vents.
Figure 2D – 18
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Bi-level Mode
Full Cold
The fan switch (1) is used to select any one of five speeds, refer to Figure 2D – 19. The side T of the MIN MAX switch
(2) has been selected resulting in full, uncontrolled cooling. The mode control switch (3) has been switched to bi-level
mode and the A/C switch (4) is on. All of these settings are displayed on the multi-function display (5).
The recirculation door (6) is closed allowing outside air (7) to enter and flow into the HVAC unit via the plenum chamber
inlet (8). Air is drawn into the HVAC unit by the blower motor (9), and is then forced through the cold evaporator fins (10).
In full cold mode, the air mix doors (11) are positioned to allow all air to bypass the heater core (12). The air travels
through the half opened face door (13) and the fully opened demist/floor door (14). The cold air (15) is then directed
through the centre and side vents as well as to the floor ducts.
Figure 2D – 19
Full Heat
The fan switch (1) is used to select any one of five speeds, refer to Figure 2D – 20. The side S of the MIN MAX switch
(2) has been selected resulting in full, uncontrolled heating. The mode control switch (3) has been switched to bi-level
mode. All of these settings are displayed on the multi-function display (4).
The recirculation door (5) are closed allowing outside air (6) to enter and flo w into the HVAC unit via the plenum chamber
inlet (7). Air is drawn into the HVAC unit by the blower motor (8). This air is then forced through the evaporator core
fins (9). In full heat mode, the air mix doors (10) will be positioned so that all incoming air is directed through the heater
core (11). The air travels through the half opened face door (12) and the fully opened demist/floor door (13). The heated
air (14) is then directed through the centre and side vents as well as to the floor ducts.
Figure 2D – 20
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Floor Mode
Full Cold
The fan switch (1) is used to select any one of five speeds, refer to Figure 2D – 21. The side T of the MIN MAX switch
(2) has been selected resulting in full, uncontrolled coolin g. The mode control switch (3) has been switched to floor mode
and the A/C switch (4) is on. All of these settings are displayed on the multi - function display (5).
The recirculation door (6) are closed allowing outside air (7) to enter and flow into the HVAC unit via the plenum chamber
inlet (8). Air is drawn into the HVAC unit by the blower motor (9), and is then forced through the cold evaporator fins (10).
In full cold mode, the air mix doors (11) are positioned to allow all air to bypass the heater core (12). The air travels
through the demist/floor door (13). The cold air (14) is then directed to the floor ducts.
Figure 2D – 21
Full Heat
The fan switch (1) is used to select any one of five speeds, refer to Figure 2D – 22. The side S of the MIN MAX switch
(2) has been selected resulting in full, uncontrolled heatin g. The mode control switch (3) has been switched to floor
mode. All of these settings are displayed on the multi-function display (4).
The recirculation door (5) are closed allowing outside air (6) to enter and flo w into the HVAC unit via the plenum chamber
inlet (7). Air is drawn into the HVAC unit by the blower motor (8). This air is then forced through the evaporator core
fins (9). In full heat mode, the air mix doors (10) will be positioned so that all incoming air is directed through the heater
core (11). The air travels through the demist/floor door (12). The heated air (13) is then directed to the floor ducts.
Figure 2D – 22
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Blend Mode
Full Cold
The fan switch (1) is used to select any one of five speeds, refer to Figure 2D – 23. The side T of the MIN MAX switch
(2) has been selected resulting in full, uncontrolled coolin g. The mode control switch (3) has been switched to blend
mode and the A/C switch (4) is on. All of these settings are displayed on the multi-function display (5).
The recirculation door (6) are closed allowing outside air (7) to enter and flo w into the HVAC unit via the plenum chamber
inlet (8). Air is drawn into the HVAC unit by the blower motor (9), and is then forced through the cold evaporator fins (10).
In full cold mode, the air mix doors (11) are positioned to allow all air to bypass the heater core (12). The air travels
through the demist/floor door (13) which is positioned half wa y between demist and floor modes. The cold air (14) is then
directed to both the front windscreen and the floor ducts.
Figure 2D – 23
Full Heat
The fan switch (1) is used to select any one of five speeds, refer to Figure 2D – 24. The side S of the MIN MAX switch
(2) has been selected resulting in full, uncontrolled heatin g. The mode control switch (3) has been switched to blend
mode. All of these settings are displayed on the multi-function display (4).
The recirculation door (5) are closed allowing outside air (6) to enter and flo w into the HVAC unit via the plenum chamber
inlet (7). Air is drawn into the HVAC unit by the blower motor (8). This air is then forced through the evaporator core
fins (9). In full heat mode, the air mix doors (10) will be positioned so that all incoming air is directed through the heater
core (11). The air travels through the demist/floor door (12), which is positioned ha lf way between demist and floor
modes. The heated air (13) is then dir ected to both the front windscreen and the floor d ucts.
Figure 2D – 24
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Demist Mode
Full Heat and A/C Activated
The fan switch (1) is used to select any one of five speeds, refer to Figure 2D – 25. The side S of the MIN MAX switch
(2) has been selected resulting in full, uncontrolled heatin g. The demist switch (3) has been switched on and the A/C
system has been switched on automatically. All of these settings are displayed on the multi-function display (4).
The recirculation door (5) are closed allowing outside air (6) to enter and flo w into the HVAC unit via the plenum chamber
inlet (7). Air is drawn into the HVAC unit by the blower motor (8). This air is then forced through the cold evaporator core
fins (9) removing moisture from the air. In full heat mode, the air mix doors (10) are positioned to direct this dehumidified
incoming air through the heater core (11). The air travels through the open demist/floor door (12). The heated air (13) is
then directed to the front windscreen via the demist vents.
NOTE
By turning on the A/C system in this mode,
dehumidification of incoming air will take place,
demisting the front windscreen and side windows
in a shorter period.
Figure 2D – 25
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Default Mode
Loss of Vacuum Supply to HV AC Unit
If a loss of vacuum occurs within the OCC system, the HVAC unit will default to the following settings. T he ventilatio n
mode settings will remain constant regardles s of what is displayed on the multi-function display (1), refer to
Figure 2D – 26.
Regardless of recirculation switch (2) selection, the recirculation door (3) will remain closed allo wing outside air (4) to
enter and flow into the HVAC unit via the plenum chamber inlet (5). The position of the air mix doors (6) will remain
controllable as their function is electrically operated b y the air mix motor. Heated coolant will flow throug h the he ater
core (7), as vacuum is required to maintain the water valve in the cold (clo sed) position. The fan switch (8) will operate
the blower fan (9) as normal. In any position of the mode switch (10), the face door (11) will remain close d. The
demist/floor door (12) will be positioned so that all air (13) leaving the HVAC unit will be directed to the demist ducts
whether or not the demist switch (14) is select ed. Depending on the selected setting of driver's side temperature
switch (15) and/or the front passenger's side temperature switch (16), this air may be cold, warm or hot.
Figure 2D – 26
