Automatic Air Conditioner: Overview Infiniti QX56 I

A/C Identification Label

Vehicles with factory installed fluorescent dye have this identification label on the underside of hood.

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Description

The front air control provides automatic regulation of the vehicle's interior temperature. The system is based on the driver's and passenger's selected "set temperature", regardless of the outside temperature changes. This is done by utilizing a microcomputer, also referred to as the front air control, which receives input signals from the following six sensors

1. Ambient sensor
2. In-vehicle sensor
3. Intake sensor
4. Optical sensor (one sensor for driver and passenger side)
5. PBR (Position Balanced Resistor).
6. Vehicle speed sensor

The front air control uses these signals (including the set temperature) to automatically control

1. Outlet air volume
2. Air temperature
3. Air distribution

The front air control also provides separate regulation of the vehicle's interior temperature for the rear passenger area. The system is based on the temperature and rear blower settings selected from rear control switches located on the front air control, or from the temperature and rear blower settings selected from rear control switches on the rear air control, when the front air control switches are set to the rear position.

The front air control is used to select

1. Outlet air volume
2. Air temperature/distribution

Description of Control System

The control system consists of input sensors, switches, the front air control (microcomputer) and outputs.

The relationship of these components is shown in the figure below

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CAN Communication System Description

Refer to " CAN COMMUNICATION ".

CONSULT-II BASIC OPERATION

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1. With the ignition switch OFF, connect CONSULT-II and "CONSULT-II CONVERTER" to the data link connector, and turn the ignition switch ON.
2. Touch "START (NISSAN BASED VHCL)".
3. Touch "HVAC" on "SELECT SYSTEM" screen. If "HVAC" is not indicated, go to " «CONSULT-II DATA LINK CONNECTOR (DLC) CIRCUIT»(ref-230033-S24487423402006042600000) ".

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1. Touch "SELF-DIAG RESULTS" on "SELECT DIAG MODE" screen to view all set DTC's.

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1. Touch "DATA MONITOR" on "SELECT DIAG MODE" screen.
2. Touch either "MAIN SIGNALS" or "SELECTION FROM MENU" on "DATA MONITOR" screen. DATA MONITOR - OPERATION PROCEDURE All signals Monitors all the items. Selection from menu Selects and monitors the individual item selected.
3. When "SELECTION FROM MENU" is selected, touch items to be monitored. When "ALL SIGNALS" is selected, all the items will be monitored.
4. Touch "START".
5. Touch "RECORD" while monitoring, then the status of the monitored item can be recorded. To stop recording, touch "STOP".

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DATA MONITOR - DISPLAY ITEM LIST

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1. With the ignition switch OFF, connect CONSULT-II and "CONSULT-II CONVERTER" to the data link connector, and turn the ignition switch ON.
2. Touch "START (NISSAN BASED VHCL)".
3. Touch "BCM" on "SELECT SYSTEM" screen. If "BCM" is not indicated, go to " «CONSULT-II DATA LINK CONNECTOR (DLC) CIRCUIT»(ref-230033-S24487423402006042600000) ".

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1. Touch "AIR CONDITIONER" on "SELECT TEST ITEM" screen.
2. Touch "DATA MONITOR" on "SELECT DIAG MODE" screen.
3. Touch either "ALL SIGNALS" or "SELECTION FROM MENU" on "DATA MONITOR" screen. DATA MONITOR - OPERATION PROCEDURE All signals Monitors all the items. Selection from menu Selects and monitors the individual item selected.
4. When "SELECTION FROM MENU" is selected, touch items to be monitored. When "ALL SIGNALS" is selected, all the items will be monitored.
5. Touch "START".
6. Touch "RECORD" while monitoring, then the status of the monitored item can be recorded. To stop recording, touch "STOP".

The self-diagnostic system diagnoses sensors, door motors, blower motor, etc. Refer to applicable articles (items) for details. Fault codes (if any are present) will be displayed in the ambient temperature display area.

Refer to " SELF-DIAGNOSIS CODE CHART ".

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Operational Check (Front)

The purpose of the operational check is to confirm that the system operates properly.

1. Conditions: Engine running and at normal operating temperature

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1. Set the temperature to 90°F or 32°C.
2. Turn front blower control dial counterclockwise until system shuts OFF.
3. Turn ignition switch OFF.
4. Turn ignition switch ON.
5. Press the AUTO switch.
6. Confirm that the set temperature remains at previous temperature.
7. Turn front blower control counterclockwise until system shuts OFF. If NG, go to trouble diagnosis procedure for " «MEMORY FUNCTION»(ref-230064-S26983139332006042700000) ". If OK, continue with next check.

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1. Press the AUTO switch. Blower should operate on low speed. The blower symbol should have one blade lit (on display).
2. Turn the front blower control dial again, and continue checking blower speed and blower symbol until all speeds are checked.
3. Leave blower on MAX speed. If NG, go to trouble diagnosis procedure for " «DIAGNOSTIC PROCEDURE FOR BLOWER MOTOR»(ref-230064-S09800745392006042700000) ". If OK, continue with next check.

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1. Press MODE switch four times and the DEF switch.
2. Each position indicator should change shape (on display).
3. Confirm that discharge air comes out according to the air distribution table. Refer to " «DISCHARGE AIR FLOW»(ref-230064-S08863171132006042700000) ".

Mode door position is checked in the next step.

If NG, go to trouble diagnosis procedure for " MODE DOOR MOTOR CIRCUIT ".

If OK, continue the check.

Note. Confirm that the compressor clutch is engaged (sound or visual inspection) and intake door position is at fresh when the DEF or D/F is selected.

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Operational Check (Rear)

The purpose of the operational check is to confirm that the system operates properly.

1. Conditions: Engine running and at normal operating temperature

System Operation

The mode door position (vent, B/L, foot, and defrost) is set by the front air control by means of the mode door motor. When a mode door position is selected on the front air control, voltage is applied to one circuit of the mode door motor while ground is applied to the other circuit, causing the mode door motor to rotate. The direction of rotation is determined by which circuit has voltage applied to it, and which one has ground applied to it.

The front air control monitors the mode door position by measuring the voltage signal on the PBR circuit.

In AUTO mode the mode door position is set by the front air control which determines the proper position based on inputs from the in-vehicle sensor, ambient sensor, optical sensor, intake sensor, and the temperature selected by the driver or passenger.

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The front air control receives data from the temperature selected by the driver side, passenger side, and rear.

The front air control then applies a voltage to one circuit of the appropriate air mix door motor, while ground is applied to the other circuit, causing the appropriate air mix door motor to rotate. The direction of rotation is determined by which circuit has voltage applied to it, and which one has ground applied to it. The front air control monitors the air mix door positions by measuring the voltage signal on the PBR circuits of each door.

In AUTO mode the air mix, intake, mode door, and defrost door positions are set by the front air control which determines the proper position based on inputs from the in-vehicle sensor, ambient sensor, optical sensor, intake sensor, and the temperature selected by the driver and front and rear passengers.

Subsequently, HOT/COLD or DEFROST/VENT or FRESH/RECIRCULATION operation is selected. The new door position data is returned to the front air control.

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The intake door control determines the intake door position based on the position of the recirculation switch. When the recirculation switch is depressed the intake door motor rotates closing off the fresh air inlet and recirculating the cabin air. If the recirculation switch is depressed again, the intake door motor rotates in the opposite direction, again allowing fresh air into the cabin.

In the AUTO mode, the front air control determines the intake door position based on the ambient temperature, the intake air temperature and the in-vehicle temperature. When the DEFROST, or OFF switches are pushed or A/C switch is OFF, the front air control sets the intake door at the fresh position.

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The front air control determines defroster door position based on the position of the defroster switch. When the defroster switch is depressed, the defroster door motor rotates directing air to the defroster ducts. When any mode other than defroster is selected, the defroster motor rotates in the opposite direction closing off air flow to the defroster ducts.

In the AUTO mode, the front air control determines defroster door position based on the ambient temperature, the intake air temperature and the in-vehicle temperature.

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SYSTEM DESCRIPTION

The front air control controls compressor operation based on ambient and intake temperature and a signal from ECM.

COMPONENT DESCRIPTION

Water Valve

The water valve cuts the flow of engine coolant to the front and rear heater cores to allow for maximum cooling during A/C operation. It is controlled by the front air control through the water valve relay.

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1. CHECK WATER VALVE RELAY POWER INPUT CIRCUITS Turn ignition switch OFF. Disconnect water valve relay connector M7. Check voltage between water valve relay harness connector terminals and ground. OK or NG OK: GO TO 2. NG: Repair harness or connector.
2. CHECK WATER VALVE CONTROL Turn ignition switch ON. Select MAX A/C with mode switch. Check continuity between water valve relay harness connector M7 terminal 1 (W/G) and ground, as MAX A/C is switched OFF and ON. OK or NG OK: GO TO 4. NG: GO TO 3.
3. CHECK WATER VALVE CONTROL OUTPUT CIRCUIT Turn ignition switch OFF. Disconnect front air control connector M50. Check continuity between water valve relay harness connector M7 terminal 1 (W/G) and front air control harness connector M50 terminal 29 (W/G). 1 - 29: Continuity should exist. Check continuity between water valve relay harness connector M7 terminal 1 (W/G) and ground. 1 - Ground: Continuity should not exist. OK or NG OK: Replace front air control. Refer to " «FRONT AIR CONTROL»(ref-230064-S10196959272006042700000) ". NG: Repair harness or connector.
4. CHECK WATER VALVE RELAY Check water valve relay. Refer to " «WATER VALVE RELAY»(ref-230064-S29702535962006042700000) ". OK or NG OK: GO TO 5 NG: Replace water valve relay.
5. CHECK WATER VALVE GROUND CIRCUIT Turn ignition switch OFF. Disconnect water valve connector F68. Check continuity between water valve harness connector F68 terminal - (B) and ground. (-) - Ground: Continuity should exist. OK or NG OK: GO TO 6. NG: Repair harness or connector.
6. CHECK WATER VALVE POWER CIRCUIT Check continuity between water valve relay connector terminal 5 (Y/L) and water valve connector F68 terminal + (Y/L) 5 - +: Continuity should exist. Check continuity between water valve relay harness connector M7 terminal 5 (Y/L) and ground. 5 - Ground: Continuity should not exist. OK or NG OK: Replace water valve. NG: Repair harness or connector.

Ambient Sensor

The ambient sensor is attached on the radiator core support (left side). It detects ambient temperature and converts it into a resistance value which is then input into the front air control.

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In-vehicle Sensor

The in-vehicle sensor is located on instrument lower driver panel. It converts variations in temperature of passenger compartment air (drawn in through the integrated fan) into a resistance value. It is then input into the front air control.

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The optical sensor is located in the center of the defroster grille. It detects sunload entering through windshield by means of a photo diode. The sensor converts the sunload into a current value which is then input into the front air control.

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BREAK-IN OPERATION

When replacing compressor clutch assembly, always conduct the break-in operation. This is done by engaging and disengaging the clutch about 30 times. Break-in operation raises the level of transmitted torque.

See also:
• REFRIGERANT PRESSURE SENSOR