2003 NISSAN TEANA Unified meter and

TROUBLE DIAGNOSIS
ATC-71
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COMPONENT DESCRIPTION
Intake Door Motor
The intake door motor is attached to the blower unit. It rotates so that
air is drawn from inlets set by the unified meter and A/C amp. Motor
rotation is conveyed to a lever which activates the intake door.
DIAGNOSIS PROCEDURE FOR INTAKE DOOR MOTOR
SYMPTOM: Intake door motor does not operate normally.
Perform diagnosis procedure. Refer to AT C - 5 9 , "
DIAGNOSIS PROCEDURE FOR LAN CIRCUIT" .
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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, air mix door motor and intake motor)

Fan control amp.

In-vehicle sensor

Ambient sensor

Sunload sensor

Intake sensor
System Operation
Automatic Mode
In the automatic mode, the blower motor speed control signal 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.
The blower motor applied voltage ranges from approximately 3.5 volts (lowest speed) to 12 volts (highest
speed).
The control blower speed (in the range of 3.5 to 12 V), unified meter and A/C amp. supplies a gate voltage to
the fan control amp. Based on this voltage, fan control amp. controls voltage supplied to the blower motor.
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).
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ATC-74
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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 low (approx. 3.5 V). During high sunload conditions, unified meter and A/C amp. raise the blower
speed (approx. 6.5 V).
Fan Speed Control Specification
COMPONENT DESCRIPTION
Fan Control Amp.
The fan control amp. is located on the blower unit. The fan control
amp. receives a gate voltage from unified meter and A/C amp. to
steplessly maintain the blower fan motor voltage in the 3.5 to 12 volt
range.
DIAGNOSIS PROCEDURE FOR BLOWER MOTOR
SYMPTOM: Blower motor operation is malfunctioning.
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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 M48
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-79,
"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 FAN FEEDBACK CIRCUIT
1. Turn ignition switch OFF.
2. Reconnect blower motor connector.
3. Turn ignition switch ON.
4. Check voltage between unified meter and A/C amp. harness
connector M45 terminal 47 and ground.
OK or NG
OK >> GO TO 3.
NG >> GO TO 9.
3. CHECK BLOWER MOTOR
Check blower motor. Refer to AT C - 7 7 , "
Blower Motor" .
OK or NG
OK >> GO TO 4.
NG >> Replace blower motor.
4. CHECK POWER SUPPLY FOR FAN CONTROL AMP.
1. Turn ignition switch ON.
2. Check voltage between fan control amp. harness connector
M86 terminal 3 and ground.
OK or NG
OK >> GO TO 5.
NG >> Repair harness or connector.1 – Ground : Battery voltage
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47 – Ground : Battery voltage.
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Terminals
Condition Voltage (+)
(−)
Fan control
amp. connectorTe r m i n a l N o .
M86 3 GroundFan speed: 1st
speedApprox. 8 V
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5. CHECK GROUND CIRCUIT FOR FAN CONTROL AMP.
1. Turn ignition switch OFF.
2. Disconnect fan control amp. connector.
3. Check continuity between fan control amp. harness connector
M86 terminal 1 and ground.
OK or NG
OK >> GO TO 6.
NG >> Repair harness or connector.
6. CHECK FOR UNIFIED METER AND A/C AMP. OUTPUT SIGNAL
1. Reconnect fan control amp. connector.
2. Turn ignition switch ON.
3. Check voltage between fan control amp. harness connector
M86 terminal 2 and ground.
OK or NG
OK >> GO TO 9.
NG >>

If the voltage is lower than 2.5 V: GO TO 7.

If the voltage is higher than 10.5 V: GO TO 8.
7. CHECK CIRCUIT CONTINUITY BETWEEN UNIFIED METER AND A/C AMP. AND FAN CONTROL
AMP.
1. Turn ignition switch OFF.
2. Disconnect unified meter and A/C amp. connector and fan con-
trol amp. connector.
3. Check continuity between unified meter and A/C amp. harness
connector M45 terminal 60 and fan control amp. harness con-
nector M86 terminal 2.
OK or NG
OK >> Replace fan control amp.
NG >> Repair harness or connector.1 – Ground : Continuity should exist.
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Terminals
Condition Voltage (+) (−)
Fan control
amp. connectorTerminal No.
M86 2 GroundFan speed: 1st -
4th speedApprox. 2.5 -
3.5 V
Fan speed: 5th
speedApprox. 9.5 -
10.5 V
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60 – 2 : Continuity should exist.
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8. CHECK FAN CONTROL AMP.
1. Turn ignition switch OFF.
2. Disconnect fan control amp. connector.
3. Check continuity between fan control amp. connector M86 ter-
minal 2 and 1.
OK or NG
OK >> GO TO 9.
NG >> Replace fan control amp.
9. CHECK CIRCUIT CONTINUITY BETWEEN UNIFIED METER AND A/C AMP. AND FAN CONTROL
AMP.
1. Turn ignition switch OFF.
2. Disconnect unified meter and A/C amp. connector.
3. Check continuity between unified meter and A/C amp. harness
connector M45 terminal 47 and fan control amp. harness con-
nector M86 terminal 3.
OK or NG
OK >> Replace unified meter and A/C amp.
NG >> Repair harness or connector.
COMPONENT INSPECTION
Blower Motor
Confirm smooth rotation of the blower motor.

Ensure that there are no foreign particles inside the blower unit.2 – 1 : Continuity should exist.
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47 – 3 : Continuity should exist.
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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.
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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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