AIR CONDITIONER CONTROL
ATC-25
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Revision: 2006 November2007 350Z
OPERATION
The unified meter and A/C amp. receives data from each of the sensors. The unified meter and A/C amp.
sends mode door, air mix door and intake door opening angle data to the mode door motor LCU, air mix door
motor LCU and intake door motor LCU.
The mode door motor, air mix door motor and intake door motor read their respective signals according to the
address signal. Opening angle indication signals received from the unified meter and A/C amp. and each of
the motor position sensors is compared by the LCUs in each motor with the existing decision and opening
angles. Subsequently, HOT/COLD, DEF/VENT and FRE/REC operation is selected. The new selection data
are returned to the unified meter and A/C amp.
TRANSMISSION DATA AND TRANSMISSION ORDER
Unified meter and A/C amp. data is transmitted consecutively to each of the door motors following the form
shown in figure below.
Start:
Initial compulsory signal sent to each of the door motors.
Address:
Data sent from the unified meter and A/C amp. are selected according to data-based decisions made by the
air mix door motor, mode door motor and intake door motor.
If the addresses are identical, the opening angle data and error check signals are received by the door motor
LCUs. The LCUs then make the appropriate error decision. If the opening angle data have no error, door con-
trol begins.
If an error exists, the received data are rejected and corrected data received. Finally, door control is based
upon the corrected opening angle data.
Opening Angle:
Data that shows the indicated door opening angle of each door motor.
Error Check:
In this procedure, transmitted and received data are checked for errors. Error data are then compiled. The
error check prevents corrupted data from being used by the air mix door motor, the mode door motor and the
intake door motor. Error data can be related to the following symptoms.
Malfunction of electrical frequency
Poor electrical connections
Signal leakage from transmission lines
Signal level fluctuation
SJIA0264E
AIR CONDITIONER CONTROL
ATC-27
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Revision: 2006 November2007 350Z
MAGNET CLUTCH CONTROL
When A/C switch is pressed, turn fan control dial to ON or set mode control dial to D/F, D/F2 or DEF position,
unified meter and A/C amp. transmits compressor ON signal to BCM.
BCM sends compressor ON signal to ECM, via CAN communication.
ECM judges whether compressor can be turned ON, based on each sensor status (refrigerant-pressure sen-
sor signal, throttle angle, etc.). If it judges compressor can be turned ON, it sends compressor ON signal to
IPDM E/R, via CAN communication.
Upon receipt of compressor ON signal from ECM, IPDM E/R turns air conditioner relay ON to operate com-
pressor.
When sending compressor ON signal to IPDM E/R via CAN communication line, ECM simultaneously sends
compressor feedback signal to unified meter and A/C amp. via CAN communication line.
Unified meter and A/C amp., then, uses input compressor feedback signal to control air inlet.
SELF-DIAGNOSIS SYSTEM
The self-diagnosis system is built into the unified meter and A/C amp. to quickly locate the cause of malfunc-
tions.
RJIA1348E
TROUBLE DIAGNOSIS
ATC-61
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Revision: 2006 November2007 350Z
SYSTEM DESCRIPTION
Component Parts
Mode door control system components are:
Unified meter and A/C amp.
Mode door motor (LCU)
A/C LAN system (PBR built-in mode door motor, air mix door motor and intake door motor)
In-vehicle sensor
Ambient sensor
Sunload sensor
Intake sensor
System Operation
The unified meter and A/C amp. receives data from each of the sensors. The unified meter and A/C amp.
sends air mix door, mode door and intake door opening angle data to the air mix door motor LCU, mode door
motor LCU and intake door motor LCU.
The air mix door motor, mode door motor and intake door motor read their respective signals according to the
address signal. Opening angle indication signals received from the unified meter and A/C amp. and each of
the motor position sensors are compared by the LCUs in each door motor with the existing decision and open-
ing angles. Subsequently, HOT/COLD, DEF/VENT and FRE/REC operation is selected. The new selection
data are returned to the unified meter and A/C amp.
Mode Door Control Specification
*10ATC-56, "DIAGNOSIS PROCE-
DURE FOR LAN CIRCUIT"
*11AT C - 11 6 , "MODE DOOR MOTOR"*12AT C - 3 4 , "SYMPTOM TABLE"
*13ATC-100, "Intake Sensor Circuit"
RJIA1380E
RJIA1778E
ATC-64
TROUBLE DIAGNOSIS
Revision: 2006 November2007 350Z
SYSTEM DESCRIPTION
Component Parts
Air mix door control system components are:
Unified meter and A/C amp.
Air mix door motor (LCU)
A/C LAN system (PBR built-in mode door motor, air mix door motor and intake door motor)
In-vehicle sensor
Ambient sensor
Sunload sensor
Intake sensor
System Operation
The unified meter and A/C amp. receives data from each of the sensors. The unified meter and A/C amp.
sends air mix door, mode door and intake door opening angle data to the air mix door motor LCU, mode door
motor LCU and intake door motor LCU.
The air mix door motor, mode door motor and intake door motor read their respective signals according to the
address signal. Opening angle indication signals received from the unified meter and A/C amp. and each of
the motor position sensors are compared by the LCUs in each door motor with the existing decision and open-
ing angles. Subsequently, HOT/COLD, DEF/VENT and FRE/REC operation is selected. The new selection
data are returned to the unified meter and A/C amp.
Air Mix Door Control Specification
RJIA1382E
RJIA1782E
TROUBLE DIAGNOSIS
ATC-73
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Revision: 2006 November2007 350Z
4. CHECK UNIFIED METER AND A/C AMP. OUTPUT SIGNAL
1. Reconnect blower motor connector and unified meter and A/C
amp. connector.
2. Turn ignition switch ON.
3. Change the fan speed from Lo to Hi, and check the duty ratios
between blower motor harness connector M62 terminal 2 and
ground by using an oscilloscope. Normal terminal 2 drive signal
duty ratios are shown in the table below.
OK or NG
OK >> Replace blower motor after confirming the fan air flow does not change.
NG >> Replace unified meter and A/C amp.
COMPONENT INSPECTION
Blower Motor
Confirm smooth rotation of the blower motor.
Ensure that there are no foreign particles inside the blower unit.
RJIA2000E
RJIA1390E
RJIA0905E
TROUBLE DIAGNOSIS
ATC-75
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Revision: 2006 November2007 350Z
SYSTEM DESCRIPTION
Unified meter and A/C amp. controls compressor operation by ambient temperature, intake air temperature
and signal from ECM.
Low Temperature Protection Control
Unified meter and A/C amp. will turn compressor ON or OFF as determined by a signal detected by ambient
sensor and intake sensor.
When ambient temperature is higher than −2°C (28°F), the compres-
sor turns ON. The compressor turns OFF when ambient temperature
is lower than −5°C (23°F).
When intake air temperature is higher than 1°C (34°F), the compres-
sor turns ON. The compressor turns OFF when intake air tempera-
ture is lower than −5°C (23°F).
DIAGNOSIS PROCEDURE FOR MAGNET CLUTCH
SYMPTOM: Magnet clutch does not engage when A/C switch is ON.
RHA094GB
SJIA0267E
SJIA1891E
ATC-76
TROUBLE DIAGNOSIS
Revision: 2006 November2007 350Z
1. CHECK AMBIENT SENSOR CIRCUIT AND INTAKE SENSOR CIRCUIT
Check ambient sensor and intake sensor. Refer to AT C - 4 6 , "
FUNCTION CONFIRMATION PROCEDURE" ,
see No. 9.
OK or NG
OK >> GO TO 2.
NG >>
Malfunctioning ambient sensor: Refer to AT C - 9 2 , "Ambient Sensor Circuit" .
Malfunctioning intake sensor: Refer to ATC-100, "Intake Sensor Circuit" .
2. PERFORM AUTO ACTIVE TEST
Refer to PG-20, "
Auto Active Test" .
Dose the magnet clutch operate?
YES >> WITH CONSULT-III: GO TO 5.
WITHOUT CONSULT-III: GO TO 6.
NO >> Check 10A fuse (No. 79, located in IPDM E/R), and GO TO 3. Refer to PG-23, "
IPDM E/R Termi-
nal Arrangement" .
3. CHECK CIRCUIT CONTINUITY BETWEEN IPDM E/R AND COMPRESSOR
1. Turn ignition switch OFF.
2. Disconnect IPDM E/R connector and compressor connector.
3. Check continuity between IPDM E/R harness connector E8 ter-
minal 33 and compressor harness connector F24 terminal 1.
OK or NG
OK >> GO TO 4.
NG >> Repair harness or connector.
4. CHECK MAGNET CLUTCH CIRCUIT
Check for operation sound when applying battery voltage direct cur-
rent to terminal.
OK or NG
OK >> 1. Replace IPDM E/R.
2. Go to self-diagnosis procedure AT C - 4 6 , "
FUNCTION
CONFIRMATION PROCEDURE" and preform self-
diagnosis STEP-4. Confirm that magnet clutch opera-
tion normal.
NG >> 1. Replace magnet clutch.
2. Go to self-diagnosis procedure AT C - 4 6 , "
FUNCTION
CONFIRMATION PROCEDURE" and preform self-
diagnosis STEP-4. Confirm that magnet clutch operation normal.
5. CHECK BCM INPUT (COMPRESSOR ON) SIGNAL
Check compressor ON/OFF signal. Refer to AT C - 3 3 , "
CONSULT-III Function (BCM)" .
OK or NG
OK >> GO TO 8.
NG >> GO TO 6.
33 – 1 : Continuity should exist.
RJIA2004E
RJIA2005E
A/C SW ON : AIR COND SIG ON
A/C SW OFF : AIR COND SIG OFF
TROUBLE DIAGNOSIS
ATC-77
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Revision: 2006 November2007 350Z
6. CHECK CIRCUIT CONTINUITY BETWEEN BCM AND UNIFIED METER AND A/C AMP.
1. Turn ignition switch OFF.
2. Disconnect BCM connector and unified meter and A/C amp.
connector.
3. Check continuity between BCM harness connector M90 terminal
27 and unified meter and A/C amp. harness connector M50 ter-
minal 42.
OK or NG
OK >> GO TO 7.
NG >> Repair harness or connector.
7. CHECK VOLTAGE FOR UNIFIED METER AND A/C AMP. (COMPRESSOR ON SIGNAL)
1. Reconnect BCM connector and unified meter and A/C amp.
connector.
2. Turn ignition switch ON.
3. Check voltage between unified meter and A/C amp. harness
connector M50 terminal 42 and ground.
OK or NG
OK >> GO TO 8.
NG-1 >> If the voltage is approx. 5 V when A/C switch is ON: Replace unified meter and A/C amp.
NG-2 >> If the voltage is approx. 0 V when A/C switch is OFF: Replace BCM.27 – 42 : Continuity should exist.
RJIA2006E
Terminals
Condition Voltage (+)
(−) Unified meter
and A/C amp.
connectorTerminal No.
M50 42 GroundA/C switch: ON
(Blower motor oper-
ates.)Approx. 0 V
A/C switch: OFF Approx. 5 V
RJIA2007E