2001 INFINITI QX4 02 sensor

11 CHECK IN-VEHICLE SENSOR
Press(DEF) switch the second time, temperature detected by in-vehicle sensor is indicated on the display screen.
ECON shown in display indicates negative temperature reading.
NOTE:
If temperature shown on display greatly differs from actual temperature, check sensor circuit first, then inspect sensor.
RHA862H
OK or NG
OK©GO TO 12.
NG©Go to In-vehicle Sensor Circuit (HA-132).
12 CHECK INTAKE SENSOR
Press(DEF) switch the third time, temperature detected by intake sensor is indicated on the display.
NOTE:
If temperature shown on display greatly differs from actual temperature, check sensor circuit first, then inspect sensor.
RHA862HA
OK or NG
OK©GO TO 13.
NG©Go to Intake Sensor Circuit (HA-139).
TROUBLE DIAGNOSES
Self-diagnosis (Cont'd)
HA-60

14 CHECK MALFUNCTIONING SENSOR
Refer to the following chart for malfunctioning code No.
(If two or more sensors malfunction, corresponding code Nos. blink respectively two times.)
MTBL0083
*1: Conduct self-diagnosis STEP 2 under sunshine.
When conducting indoors, aim a light (more than 60W) at sunload sensor, otherwise Code No.
will indicate despite that
sunload sensor is functioning properly.
*2: HA-129
*3: HA-132
*4: HA-139
*5: HA-135
*6: HA-141
RHA455G
RHA501A
©INSPECTION END
TROUBLE DIAGNOSES
Self-diagnosis (Cont'd)
HA-62

RHA464GA
RHA858H
MAIN POWER SUPPLY AND GROUND CIRCUIT CHECKNBHA0037Component DescriptionNBHA0037S01Automatic Amplifier (Auto Amp.)NBHA0037S0101The auto amplifier has a built-in microcomputer which processes
information sent from various sensors needed for air conditioner
operation. The air mix door motor, mode door motor, intake door
motor, blower motor and compressor are then controlled.
The auto amplifier is unitized with control mechanisms. Signals
from various switches and Potentio Temperature Control (PTC) are
directly entered into auto amplifier.
Self-diagnostic functions are also built into auto amplifier to provide
quick check of malfunctions in the auto air conditioner system.
RHA464GA
RHA867H
Potentio Temperature Control (PTC)NBHA0037S0102The PTC is built into the A/C auto amp. or Display & NAVI control
unit. It can be set at an interval of 0.5ÉC (1.0ÉF) in the 18ÉC (65ÉF)
to 32ÉC (85ÉF) temperature range by pushing the temperature but-
ton. The set temperature is digitally displayed.
TROUBLE DIAGNOSES
A/C System (Cont'd)
HA-72

SYSTEM DESCRIPTION=NBHA0052Component PartsNBHA0052S01Mode door control system components are:
1) Auto amp.
2) Mode door motor (LCU)
3) In-vehicle sensor
4) Ambient sensor
5) Sunload sensor
6) Intake sensor
System OperationNBHA0052S02The auto amplifier receives data from each of the sensors. The amplifier sends air mix door and mode door
opening angle data to the air mix door motor LCU and mode door motor LCU.
The air mix door motor and mode door motor read their respective signals according to the address signal.
Opening angle indication signals received from the auto amplifier and each of the motor position sensors are
compared by the LCUs in each motor with the existing decision and opening angles. Subsequently, HOT/
COLD or DEFROST/VENT operation is selected. The new selection data is returned to the auto amplifier.
RHA870H
GI
MA
EM
LC
EC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
SC
EL
IDX
TROUBLE DIAGNOSES
Mode Door Motor (Cont'd)
HA-77

SYSTEM DESCRIPTION=NBHA0059Component PartsNBHA0059S01Air mix door control system components are:
1) Auto amp.
2) Air mix door motor (LCU)
3) In-vehicle sensor
4) Ambient sensor
5) Sunload sensor
6) Intake sensor
System OperationNBHA0059S02The auto amplifier receives data from each of the sensors. The amplifier sends air mix door and mode door
opening angle data to the air mix door motor LCU and mode door motor LCU.
The air mix door motor and mode door motor read their respective signals according to the address signal.
Opening angle indication signals received from the auto amplifier and each of the motor position sensors are
compared by the LCUs in each motor with the existing decision and opening angles. Subsequently, HOT/
COLD or DEFROST/VENT operation is selected. The new selection data is returned to the auto amplifier.
RHA872H
TROUBLE DIAGNOSES
Air Mix Door Motor (Cont'd)
HA-84

SYSTEM DESCRIPTION=NBHA0056Component PartsNBHA0056S01Intake door control system components are:
1) Auto amp.
2) Intake door motor
3) A/C LAN system (PBR built-in mode motor and air mix door motor)
4) In-vehicle sensor
5) Ambient sensor
6) Sunload sensor
7) Intake sensor
System OperationNBHA0056S02The intake door control determines intake door position based on the ambient temperature, the intake air
temperature and the in-vehicle temperature. When the ECON, DEFROST, or OFF switches are pushed, the
auto amplifier sets the intake door at the ªFreshº position.
RHA874H
Intake Door Control SpecificationNBHA0056S03
RHA136G
GI
MA
EM
LC
EC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
SC
EL
IDX
TROUBLE DIAGNOSES
Intake Door Motor (Cont'd)
HA-89

SYSTEM DESCRIPTION=NBHA0062Component partsNBHA0062S01Fan speed control system components are:
1) Auto amp.
2) Fan control amp.
3) A/C LAN system (PBR built-in mode door motor and air mix door motor)
4) In-vehicle sensor
5) Ambient sensor
6) Sunload sensor
7) Intake sensor
System OperationNBHA0062S02
SHA006FF
Automatic ModeNBHA0062S03In the automatic mode, the blower motor speed is calculated by the automatic amplifier based on inputs from
the PBR, in-vehicle sensor, sunload sensor, intake sensor and ambient sensor. The blower motor applied
voltage ranges from approximately 5 volts (lowest speed) to 12 volts (highest speed).
The control blower speed (in the range of 5 to 12V), the automatic amplifier supplies a gate voltage to the fan
control amplifier. Based on this voltage, the fan control amplifier controls the voltage supplied to the blower
motor.
Starting Fan Speed ControlNBHA0062S04Start Up From ªCOLD SOAKº Condition (Automatic mode)NBHA0062S0401In a cold start up condition where the engine coolant temperature is below 50ÉC (122ÉF), the blower will not
operate for a short period of time (up to 126 seconds). The exact start delay time varies depending on the
ambient and engine coolant temperature.
In the most extreme case (very low ambient) the blower starting delay will be 126 seconds as described above.
After this delay, the blower will operate at low speed until the engine coolant temperature rises above 55ÉC
(131ÉF), at which time the blower speed will increase to the objective speed.
Start Up From Normal or ªHOT SOAKº Condition (Automatic mode)
NBHA0062S0402The blower will begin operation momentarily after the AUTO button is pushed. The blower speed will gradu-
ally rise to the objective speed over a time period of 3 seconds or less (actual time depends on the objective
blower speed).
GI
MA
EM
LC
EC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
SC
EL
IDX
TROUBLE DIAGNOSES
Blower Motor (Cont'd)
HA-97

RHA094GB
SYSTEM DESCRIPTION=NBHA0066Auto amplifier controls compressor operation by ambient tempera-
ture and signal from ECM.
Low Temperature Protection ControlNBHA0066S01Auto amplifier will turn the compressor ªONº or ªOFFº as deter-
mined by a signal detected by ambient sensor.
When ambient temperatures are greater than ±2ÉC (28ÉF), the
compressor turns ªONº. The compressor turns ªOFFº when ambi-
ent temperatures are less than þ5ÉC (23ÉF).
RHA877H
DIAGNOSTIC PROCEDURENBHA0067SYMPTOM: 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
YesorNo
Ye s©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