2007 INFINITI M35 MOTOR

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ATC-89
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Revision: 2007 April2007 M35/M45
SYSTEM DESCRIPTION
Component Parts
Fan speed control system components are:

Unified meter and A/C amp.

A/C LAN system (PBR built-in mode door motor, upper ventilator door motor, air mix door motor and
intake door motor)

In-vehicle sensor

Ambient sensor

Sunload sensor

Intake sensor
System Operation
Automatic Mode
In the automatic mode, the blower motor speed is calculated by the unified meter and A/C amp. based on the
input from the PBR, in-vehicle sensor, sunload sensor, intake sensor and ambient sensor.
When the air flow is increased, the duty ratio of the blower fan motor’s drive signal is changed at 8%/sec. to
prevent a sudden increase in air flow.
In addition to manual air flow control and the usual automatic air flow control, starting air flow control, low
water temperature starting control and high passenger compartment temperature starting control are avail-
able.
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ATC-90
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Revision: 2007 April2007 M35/M45
Starting Fan Speed Control
Start up from COLD SOAK Condition (Automatic mode)
In a cold start up condition where the engine coolant temperature is below 56°C (133°F), the blower will not
operate for a short period of time (up to 150 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 150 seconds as described
above. After this delay, the blower will operate at low speed until the engine coolant temperature rises above
56°C (133°F), and then the blower speed will increase to the objective speed.
Start up from usual or HOT SOAK Condition (Automatic mode)
The blower will begin operation momentarily after the AUTO switch is pressed. 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).
Blower Speed Compensation
Sunload
When the in-vehicle temperature and the set temperature are very close, the blower will be operating at low
speed. The low speed will vary depending on the sunload. During conditions of low or no sunload, the blower
speed is at duty ratio 25%. During high sunload conditions, the unified meter and A/C amp. raise the blower
speed (duty ratio 49%).
Fan Speed Control Specification
COMPONENT DESCRIPTION
Brush-less Motor
The blower motor utilizes a brush-less motor with a rotating magnet.
Quietness is improved over previous motors where the brush was
the point of contact and the coil rotated.
DIAGNOSIS PROCEDURE FOR BLOWER MOTOR
SYMPTOM: Blower motor operation is malfunctioning.
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ZHA152H
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Revision: 2007 April2007 M35/M45
1. CHECK POWER SUPPLY FOR BLOWER MOTOR
1. Disconnect blower motor connector.
2. Turn ignition switch ON.
3. Check voltage between blower motor harness connector M91
terminal 1 and ground.
OK or NG
OK >> GO TO 2.
NG >> Check power supply circuit and 15A fuses [Nos. 10 and
11, located in the fuse block (J/B)]. Refer to PG-114,
"FUSE BLOCK - JUNCTION BOX (J/B)" .

If fuses are OK, check harness for open circuit. Repair or replace if necessary.

If fuses are NG, check harness for short circuit and replace fuse.
2. CHECK BLOWER MOTOR GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Check continuity between blower motor harness connector M91
terminal 3 and ground.
OK or NG
OK >> GO TO 3.
NG >> Repair harness or connector.
3. CHECK CIRCUIT CONTINUITY BETWEEN BLOWER MOTOR AND UNIFIED METER AND A/C AMP.
1. Disconnect unified meter and A/C amp. connector.
2. Check continuity between blower motor harness connector M91
terminal 2 and unified meter and A/C amp. harness connector
M64 terminal 38.
OK or NG
OK >> GO TO 4.
NG >> Repair harness or connector.1 – Ground : Battery voltage
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3 – Ground : Continuity should exist.
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2 – 38 : Continuity should exist.
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ATC-92
TROUBLE DIAGNOSIS
Revision: 2007 April2007 M35/M45
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. Set MODE switch to VENT position.
4. Change the fan speed from Lo to Hi, and check the duty ratios
between blower motor harness connector M91 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.
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ATC-96
TROUBLE DIAGNOSIS
Revision: 2007 April2007 M35/M45
5. CHECK BCM INPUT (COMPRESSOR ON) SIGNAL
Check compressor ON/OFF signal. Refer to AT C - 4 0 , "
CONSULT-II
Function (ECM)" .
OK or NG
OK >> GO TO 8.
NG >> GO TO 6.
6. CHECK REFRIGERANT PRESSURE SENSOR
WITH CONSULT-II
1. Start the engine.
2. Check voltage of refrigerant pressure sensor. Refer to EC-138, "
CONSULT-II Reference Value in Data
Monitor" (VQ35DE) or EC-841, "CONSULT-II Reference Value in Data Monitor" (VK45DE).
WITHOUT CONSULT-II
1. Start the engine.
2. Check voltage between ECM harness connector F108 terminal
70 and ground.
OK or NG
OK >>
WITH CONSULT-II: GO TO 7.

WITHOUT CONSULT-II: Repair harness or connector.
NG >> Refer to EC-704, "
REFRIGERANT PRESSURE SENSOR" (VQ35DE) or EC-1424, "REFRIGER-
ANT PRESSURE SENSOR" (VK45DE).
7. CHECK ECM INPUT (FAN ON) SIGNAL
Check FAN ON/OFF signal. Refer to AT C - 4 0 , "
CONSULT-II Function
(ECM)" .
OK or NG
OK >> GO TO 8.
NG >> Repair harness or connector.A/C SW ON : AIR COND SIG ON
A/C SW OFF : AIR COND SIG OFF
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Terminals
Condition Voltage (+)
(−)
ECM
connectorTerminal
No.
F108 70 GroundA/C switch: ON
(Blower motor operates.)Approx. 1.0 -
4.0 V
PBIB1188E
FAN SW ON : HEATER FAN SW ON
FAN SW OFF : HEATER FAN SW OFF
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Revision: 2007 April2007 M35/M45
*1ATC-57, "FUNCTION CONFIRMA-
TION PROCEDURE", see No. 2 to 6.*2ATC-82, "
Air Mix Door Motor Circuit"*3ATC-102, "Test Reading
(VQ35DE)" or ATC-103, "Test
Reading (VK45DE)"
*4ATC-63, "AUXILIARY MECHA-
NISM: TEMPERATURE SETTING
TRIMMER"
*5ATC-57, "FUNCTION CONFIRMA-
TION PROCEDURE", see No. 13.*6ATC-71, "
LAN System Circuit"
*7ATC-88, "Blower Motor Circuit"*8ATC-93, "Magnet Clutch Circuit"*9ATC-100, "PERFORMANCE TEST
DIAGNOSIS"
*10ATC-65, "Operational Check"*11AT C - 7 , "CONTAMINATED REFRIG-
ERANT"
*12EM-16, "Checking Drive Belts"
(VQ35DE) or EM-174, "
Checking
Drive Belts" (VK45DE)
*13EC-499, "
SYSTEM DESCRIPTION"
(VQ35DE) or EC-1214, "
SYSTEM
DESCRIPTION" (VK45DE)

ATC-100
TROUBLE DIAGNOSIS
Revision: 2007 April2007 M35/M45
PERFORMANCE TEST DIAGNOSIS
*1ATC-102, "PERFORMANCE
CHART"
*2ATC-102, "PERFORMANCE
CHART"
*3ATC-104, "TROUBLE DIAGNOSIS
FOR UNUSUAL PRESSURE"
*4ATC-82, "Air Mix Door Motor Circuit"
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Revision: 2007 April2007 M35/M45
*1ATC-156, "Check Disc to Pulley
Clearance"
*2ATC-88, "Blower Motor Circuit"*3EM-16, "Checking Drive Belts"
(VQ35DE) or EM-174, "
Checking
Drive Belts" (VK45DE)
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