2001 INFINITI QX4 IDX

1 CHECK IN-VEHICLE SENSOR CIRCUIT BETWEEN IN-VEHICLE SENSOR AND BODY GROUND
Disconnect in-vehicle sensor harness connector.
Do approx. 5 volts exist between in-vehicle sensor harness terminal No. 1 and body ground?
RHA477G
YesorNo
Ye s©GO TO 2.
No©GO TO 4.
2 CHECK IN-VEHICLE SENSOR CIRCUIT BETWEEN IN-VEHICLE SENSOR AND AUTO AMP. (LCU)
1. Disconnect auto amp. (LCU) harness connector.
2. Check circuit continuity between in-vehicle sensor harness terminal No. 2 and auto amp. (LCU) harness terminal No.
11 or 9.
RHA831H
Continuity should exist.
If OK, check harness for short.
OK or NG
OK©GO TO 3.
NG©Repair harness or connector.
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TROUBLE DIAGNOSES
In-vehicle Sensor Circuit (Cont'd)
HA-133

RHA060GB
COMPONENT INSPECTIONNBHA0045In-vehicle SensorNBHA0045S01After disconnecting in-vehicle sensor harness connector, measure
resistance between terminals 1 and 2 at sensor harness side, using
the table below.
Temperature ÉC (ÉF) Resistance kW
þ15 (5) 12.73
þ10 (14) 9.92
þ5 (23) 7.80
0 (32) 6.19
5 (41) 4.95
10 (50) 3.99
15 (59) 3.24
20 (68) 2.65
25 (77) 2.19
30 (86) 1.81
35 (95) 1.51
40 (104) 1.27
45 (113) 1.07
If NG, replace in-vehicle sensor.
RHA639F
Sunload Sensor Circuit
COMPONENT DESCRIPTIONNBHA0046The sunload sensor is located on the right 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 auto amplifier.
SUNLOAD INPUT PROCESSNBHA0047The auto amp. also includes a processing circuit which ªaverageº
the variations in detected sunload over a period of time. This pre-
vents drastic swings in the ATC system operation due to small or
quick variations in detected sunload.
For example, consider driving along a road bordered by an occa-
sional group of large trees. The sunload detected by the sunload
sensor will vary whenever the trees obstruct the sunlight. The pro-
cessing circuit averages the detected sunload over a period of
time, so that the (insignificant) effect of the trees momentarily
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TROUBLE DIAGNOSES
In-vehicle Sensor Circuit (Cont'd)
HA-135

2 CHECK SUNLOAD SENSOR CIRCUIT BETWEEN SUNLOAD SENSOR AND AUTO AMP. (LCU)
1. Disconnect auto amp. (LCU) harness connector.
2. Check circuit continuity between sunload sensor harness terminal No. 2 and auto amp. (LCU) harness terminal No. 11
or 9.
RHA833H
Continuity should exist.
If OK, check harness for short.
OK or NG
OK©GO TO 3.
NG©Repair harness or connector.
3 CHECK SUNLOAD SENSOR.
Refer to HA-138.
OK or NG
OK©1. Replace auto amp. (LCU).
2. Go to self-diagnosis step-by-step procedure (HA-45) and perform self-diagnosis STEP
2.
Confirm that code No. 20 is displayed.
NG©1. Replace sunload sensor.
2. Go to self-diagnosis step-by-step procedure (HA-45) and perform self-diagnosis STEP
2.
Confirm that code No. 20 is displayed.
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TROUBLE DIAGNOSES
Sunload Sensor Circuit (Cont'd)
HA-137

SHA930E
RHA584E
Intake Sensor Circuit
COMPONENT DESCRIPTIONNBHA0105Intake SensorNBHA0105S01The intake sensor is located on the cooling unit. It converts tem-
perature of air after it passes through the evaporator into a resis-
tance value which is then input to the auto amp.
After disconnecting intake sensor harness connector, measure
resistance between terminals 1 and 2 at sensor harness side, using
the table below.
Temperature ÉC (ÉF) Resistance kW
þ15 (5) 12.73
þ10 (14) 9.92
þ5 (23) 7.80
0 (32) 6.19
5 (41) 4.95
10 (50) 3.99
15 (59) 3.24
20 (68) 2.65
25 (77) 2.19
30 (86) 1.81
35 (95) 1.51
40 (104) 1.27
45 (113) 1.07
If NG, replace intake sensor.
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TROUBLE DIAGNOSES
Sunload Sensor Circuit (Cont'd)
HA-139

3 CHECK INTAKE SENSOR
Refer to HA-139.
OK or NG
OK©1. Replace auto amp.
2. Go to self-diagnosis step-by-step procedure (HA-45) and perform self-diagnosis STEP
2.
Confirm that code No. 20 is displayed.
NG©1. Replace intake sensor.
2. Go to self-diagnosis step-by-step procedure (HA-45) and perform self-diagnosis STEP
2.
Confirm that code No. 20 is displayed.
4 CHECK INTAKE SENSOR CIRCUIT BETWEEN AMBIENT SENSOR AND AUTO AMP. (LCU)
1. Disconnect auto amp. (LCU) harness connector.
2. Check circuit continuity between intake sensor harness terminal No. 1 and auto amp. (LCU) harness terminal No. 1.
RHA837H
Continuity should exist.
If OK, check harness for short.
OK or NG
OK©1. Replace auto amp.
2. Go to self-diagnosis step-by-step procedure (HA-45) and perform self-diagnosis STEP
2.
Confirm that code No. 20 is displayed.
NG©Repair harness or connector.
Air Mix Door Motor PBR Circuit
DIAGNOSTIC PROCEDURENBHA0050For description of mode door motor and air mix door motor circuit,
refer to HA-84.
SYMPTOM: If PBR circuit is open or shorted. (þ
oris
indicated on the display as a result of conducting Self-diag-
nosis STEP 2.)
Perform diagnostic procedure for mode door motor and air
mix door motor. Refer to HA-78.
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TROUBLE DIAGNOSES
Intake Sensor Circuit (Cont'd)
HA-141

3 CHECK MULTIPLEX COMMUNICATION SIGNAL
Do approx. 3.5 volts exist between auto amp. harness terminal No. 40 and body ground?
RHA891H
YesorNo
Ye s©INSPECTION END.
No©1. Replace Display & NAVI control unit.
2. Go to ªOPERATIONAL CHECKº, HA-66.
Confirm that A/C system is in good order.
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TROUBLE DIAGNOSES
Multiplex Communication Circuit (Cont'd)
HA-143

SHA251FA
*1: HA-146
*2: HA-155*3: HA-157
*4: HA-114*5: HA-2
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SERVICE PROCEDURE
HFC-134a (R-134a) Service Procedure (Cont'd)
HA-145

4 CHECK ANY PART
Is there any part to be replaced? (Evaporator, condenser, liquid tank or in case there is evidence of a large amount of
lubricant leakage.)
YesorNo
Ye s©Go to ªLubricant Adjusting Procedure for Components Replacement Except
Compressorº, (HA-148).
No©Carry out the A/C performance test.GI
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SERVICE PROCEDURE
Maintenance of Lubricant Quantity in Compressor (Cont'd)
HA-147