Infiniti QX4 (R50). Manual — part 477
RHA094GB
SYSTEM DESCRIPTION
=NBHA0066
Auto amplifier controls compressor operation by ambient tempera-
ture and signal from ECM.
Low Temperature Protection Control
NBHA0066S01
Auto amplifier will turn the compressor “ON” or “OFF” as deter-
mined by a signal detected by ambient sensor.
When ambient temperatures are greater than –2°C (28°F), the
compressor turns “ON”. The compressor turns “OFF” when ambi-
ent temperatures are less than −5°C (23°F).
RHA877H
DIAGNOSTIC PROCEDURE
NBHA0067
SYMPTOM: Magnet clutch does not engage when AUTO
switch is ON.
1
CHECK POWER SUPPLY FOR COMPRESSOR
Disconnect compressor harness connector. Do approx. 12 volts exist between compressor harness terminal No. 1 and
body ground?
RHA096G
Yes or No
Yes
©
Check magnet clutch coil.
1. If NG, replace magnet clutch. Refer to HA-150.
2. Go to self-diagnosis step-by-step procedure (HA-45) and perform self-diagnosis STEP
4.
Confirm that magnet clutch operation is normal.
No
©
Disconnect A/C relay. And GO TO 2.
TROUBLE DIAGNOSES
Magnet Clutch (Cont’d)
HA-106
2
CHECK CIRCUIT CONTINUITY BETWEEN A/C RELAY AND COMPRESSOR
Check circuit continuity between A/C relay harness terminal No. 5 and compressor harness terminal No. 1.
RHA748FB
Continuity should exist.
If OK, check harness for short.
OK or NG
OK
©
GO TO 3.
NG
©
Repair harness or connector.
3
CHECK POWER SUPPLY FOR A/C RELAY
Disconnect A/C relay.
Do approx. 12 volts exist between A/C relay harness terminal Nos. 2, 3 and body ground?
RHA614F
Yes or No
Yes
©
GO TO 4.
No
©
Check power supply circuit and 7.5A (No. 6) fuse at fuse block.
Refer to EL-14, “Wiring Diagram — POWER —”.
I
If OK, check for open circuit in wiring harness.
Repair or replace as necessary.
I
If NG, replace fuse and check wiring harness for short circuit.
Repair or replace as necessary.
4
CHECK A/C RELAY AFTER DISCONNECTING IT
Refer to HA-110.
OK or NG
OK
©
Reconnect A/C relay. And GO TO 5.
NG
©
1. Replace A/C relay.
2. Go to self-diagnosis step-by-step procedure (HA-45) and perform self-diagnosis STEP
4.
Confirm that magnet clutch operation is normal.
GI
MA
EM
LC
EC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
SC
EL
IDX
TROUBLE DIAGNOSES
Magnet Clutch (Cont’d)
HA-107
5
CHECK COIL SIDE CIRCUIT OF A/C RELAY
Do approx. 12 volts exist between ECM harness terminal No. 27 and body ground?
RHA482GG
Yes or No
Yes
©
GO TO 6.
No
©
Disconnect A/C relay.
Disconnect ECM harness connector.
GO TO 11.
6
CHECK VOLTAGE FOR ECM
Do approx. 12 volts exist between ECM harness terminal No. 45 and body ground?
RHA701FJ
Yes or No
Yes
©
Disconnect ECM harness connector.
Disconnect dual-pressure switch harness connector.
GO TO 7.
No
©
Check ECM. Refer to EC-127, “ECM Terminals and Reference Value”.
TROUBLE DIAGNOSES
Magnet Clutch (Cont’d)
HA-108
7
CHECK CIRCUIT CONTINUITY BETWEEN ECM AND AUTO AMP.
Check circuit continuity between ECM harness terminal No. 45 and auto amp. harness terminal No. 22.
RHA878H
Continuity should exist.
If OK, check harness for short.
OK or NG
OK
©
GO TO 8.
NG
©
1. Repair harness or connector.
2. Go to “STEP-BY-STEP PROCEDURE”, “Self-diagnosis”, HA-45 and perform self-diag-
nosis STEP 4.
Confirm that magnet clutch operation is normal.
8
CHECK REFRIGERANT PRESSURE SENSOR
Refer to EC-641, “Diagnostic Procedure”, HA-111.
OK or NG
OK
©
GO TO 9.
NG
©
Replace refrigerant pressure sensor.
9
CHECK VOLTAGE FOR ECM
Check 4.6 volts exist between ECM harness terminal No. 51 and body ground?
RHA482GG
Yes or No
Yes
©
Check ECM. Refer to EC-127, “ECM Terminal and Reference Value”.
No
©
GO TO 10.
GI
MA
EM
LC
EC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
SC
EL
IDX
TROUBLE DIAGNOSES
Magnet Clutch (Cont’d)
HA-109
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