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TROUBLE DIAGNOSIS
ATC-79
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SYSTEM DESCRIPTION
Unified meter and A/C amp. controls compressor operation by intake air temperature and signal from ECM.
Low Temperature Protection Control
Unified meter and A/C amp. will turn the compressor ON or OFF as determined by a signal detected by intake
sensor.
When intake air temperature is higher than 4°C (39°F), the compres-
sor turns ON. The compressor turns OFF when intake air tempera-
ture is lower than 2.5°C (37°F).
DIAGNOSIS PROCEDURE FOR MAGNET CLUTCH
SYMPTOM: Magnet clutch does not engage when A/C switch is ON.
1. CHECK INTAKE SENSOR CIRCUIT
Check intake sensor. Refer to AT C - 4 7 , "
FUNCTION CONFIRMATION PROCEDURE" , see No. 11.
OK or NG
OK >> GO TO 2.
NG >> Malfunctioning intake sensor: Refer to ATC-105, "
Intake Sensor Circuit" .
2. PERFORM AUTO ACTIVE TEST
Refer to PG-21, "
Auto Active Test" .
Does the magnet clutch operate?
YES >>WITH CONSULT-II: GO TO 5.
WITHOUT CONSULT-II: GO TO 6.
NO >> Check 10 A fuse (No. 79, located in IPDM E/R). Refer to PG-25, "
IPDM E/R Terminal Arrange-
ment" , and GO TO 3.
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ATC-80
TROUBLE DIAGNOSIS
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 F2 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 7 , "
FUNCTION
CONFIRMATION PROCEDURE" and perform self-
diagnosis STEP-4. Confirm that magnet clutch opera-
tion normal.
NG >> 1. Replace compressor. Refer to ATC-134, "
Removal
and Installation of Compressor" .
2. Go to self-diagnosis procedure AT C - 4 7 , "
FUNCTION
CONFIRMATION PROCEDURE" and perform 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 4 , "
CONSULT-II
Function (BCM)" .
OK or NG
OK >> GO TO 8.
NG >> GO TO 6.
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 M3 terminal
27 and unified meter and A/C amp. harness connector M45 ter-
minal 42.
OK or NG
OK >> GO TO 7.
NG >> Repair harness or connector.33 – 1 : Continuity should exist.
RJIA2004E
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A/C SW ON : AIR COND SW ON
A/C SW OFF : AIR COND SW OFF
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27 – 42 : Continuity should exist.
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TROUBLE DIAGNOSIS
ATC-81
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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 M45 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.
8. CHECK REFRIGERANT PRESSURE SENSOR
WITH CONSULT-II
1. Start the engine.
2. Check voltage of refrigerant pressure sensor. Refer to EC-90,
"CONSULT-II Reference Value in Data Monitor Mode" (QR
engine) or EC-434, "
CONSULT-II Reference Value in Data Mon-
itor Mode" (VQ engine).
WITHOUT CONSULT-II
1. Start the engine.
2. Check voltage between ECM harness connector F101 terminal
70 and ground.
OK or NG
OK >>WITH CONSULT-II: GO TO 9.
WITHOUT CONSULT-II: GO TO 10.
NG >> Refer to EC-339, "
REFRIGERANT PRESSURE SENSOR" (QR engine) or EC-748, "REFRIGER-
ANT PRESSURE SENSOR" (VQ engine).
Te r m i n a l s
Condition Voltage (+)
(-) Unified meter
and A/C amp.
connectorTerminal
No.
M45 42 GroundA/C switch: ON
(Blower motor oper-
ates.)Approx. 0 V
OFF switch: ON (A/C
System: OFF)Approx. 5 V
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Terminals
Condition Voltage (+)
(-)
ECM con-
nectorTerminal No.
F10169 (QR engine)
GroundA/C switch: ON
(Blower motor
operates.)Approx. 1.0 - 4.0 V
70 (VQ engine)
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ATC-82
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9. CHECK BCM INPUT (FAN ON) SIGNAL
Check FAN ON/OFF signal. Refer to AT C - 3 4 , "
CONSULT-II Function
(BCM)" .
OK or NG
OK >> GO TO 12.
NG >> GO TO 10.
10. 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 M3 terminal
28 and unified meter and A/C amp. harness connector M45 ter-
minal 57.
OK or NG
OK >> GO TO 11.
NG >> Repair harness or connector.
11 . CHECK VOLTAGE FOR UNIFIED METER AND A/C AMP. (FAN 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 M45 terminal 57 and ground.
OK or NG
OK >> GO TO 12.
NG-1 >> If the voltage is approx. 5 V when blower motor is ON: Replace unified meter and A/C amp.
NG-2 >> If the voltage is approx. 0 V when blower motor is OFF: Replace BCM.FAN CONTROL SW ON : FAN ON SIG ON
FAN CONTROL SW OFF : FAN ON SIG OFF
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28 – 57 : Continuity should exist.
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Terminals
Condition Voltage (+)
(-) Unified meter
and A/C amp.
connectorTerminal No.
M45 57 GroundAUTO switch: ON
(Blower motor
operates.)Approx. 0 V
OFF switch: ON
(A/C system: OFF)Approx. 5 V
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TROUBLE DIAGNOSIS
ATC-83
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12. CHECK CAN COMMUNICATION
Check CAN communication. Refer to BCS-14, "
CAN Communication Inspection Using CONSULT-II (Self-
Diagnosis)" .
BCM – ECM
ECM – IPDM E/R
ECM – Unified meter and A/C amp.
OK or NG
OK >> Replace ECM.
NG >> Repair or replace malfunctioning part(s).
COMPONENT INSPECTION
Refrigerant Pressure Sensor
The refrigerant pressure sensor is attached to the condenser.
Make sure that the A/C refrigerant pressure and the sensor output
voltage are as shown in the A/C operating condition figure. Refer to
EC-339, "
REFRIGERANT PRESSURE SENSOR" (QR engine) or
EC-748, "
REFRIGERANT PRESSURE SENSOR" (VQ engine).
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ATC-84
TROUBLE DIAGNOSIS
Insufficient CoolingBJS000G7
SYMPTOM: Insufficient cooling
INSPECTION FLOW
*1AT C - 4 7 , "FUNCTION CONFIRMA-
TION PROCEDURE", see No. 2 to 6.*2ATC-66, "
Air Mix Door Motor Circuit"*3ATC-87, "Test Reading"
*4AT C - 5 2 , "AUXILIARY MECHANISM:
TEMPERATURE SETTING TRIM-
MER"
*5ATC-47, "FUNCTION CONFIRMA-
TION PROCEDURE", see No. 13.*6ATC-59, "
LAN System Circuit"
*7AT C - 7 2 , "Blower Motor Circuit"*8ATC-78, "Magnet Clutch Circuit"*9ATC-85, "PERFORMANCE TEST
DIAGNOSIS"
*10AT C - 5 4 , "Operational Check"*11EM-14, "Checking Drive Belts" (QR
engine) or EM-128, "
Checking Drive
Belts" (VQ engine)*12EC-218, "
System Description" (QR
engine) or EC-575, "
System
Description" (VQ engine)
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TROUBLE DIAGNOSIS
ATC-85
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PERFORMANCE TEST DIAGNOSIS
*1AT C - 8 7 , "PERFORMANCE CHART"*2ATC-87, "PERFORMANCE CHART"*3AT C - 8 8 , "TROUBLE DIAGNOSIS
FOR UNUSUAL PRESSURE"
*4AT C - 6 6 , "Air Mix Door Motor Circuit"
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ATC-86
TROUBLE DIAGNOSIS
*1ATC-136, "Check Disc to Pulley
Clearance"
*2ATC-72, "Blower Motor Circuit"*3EM-14, "Checking Drive Belts" (QR
engine) or EM-128, "
Checking Drive
Belts" (VQ engine)
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