A/c-Heater System - Automatic: Other Infiniti J30 I

AIR MIX DOOR MOTOR

Air mix door motor is attached to heater unit. Door motor rotates into position by commands received from the auto amplifier (system control panel). Motor rotation is transferred through a shaft. Door position (angle) is fed back to auto amplifier by the Potentiometer Balance Resistor (PBR). The PBR is located inside air mix door motor.

AMBIENT TEMPERATURE SENSOR

Ambient temperature sensor is attached to the left front side of the condenser. This sensor senses ambient temperature and converts temperature reading into a resistance value. Resistance value is sent to auto amplifier (system control panel).

If auto amplifier detects an abrupt ambient temperature change, it will gradually adjust temperature until desired setting is reached. If, for example, the vehicle is stopped in traffic after traveling at highway speeds, ambient temperature sensor will detect high ambient temperature from heat radiating from radiator. To prevent an unpleasant change in A/C operation from this sudden change in ambient temperature, ambient temperature input process will gradually adjust the temperature.

ASPIRATOR

Aspirator is located below side link of heater unit. Aspirator produces a vacuum from air being discharged from heater unit. This vacuum pulls air from passenger compartment into the aspirator.

AUTO AMPLIFIER (SYSTEM CONTROL PANEL)

The auto amplifier (system control panel) has a built-in microcomputer that processes information from various sensors. The auto amplifier controls air mix door motor, mode door motor, intake door motor, fan motor and compressor operation. Self-diagnostic functions are built into the auto amplifier to check malfunctions in A/C-heater system. (Scheme 2)

The auto amplifier detects sensor voltage by monitoring an internal, fixed resistor. A voltage of 12 volts is reduced to 5 volts by a constant voltage circuit, where it is applied to ground through the fixed resistor and sensor.

Scheme 2

FAN CONTROL AMPLIFIER

Located in evaporator housing, fan control amplifier amplifies base current flowing from auto amplifier (system control panel). This change in base current changes blower speed. Voltage range is 5-10.5 volts. At voltage greater than 10.5 volts, high-speed relay applies a direct ground to blower motor.

HIGH-SPEED RELAY

Note. The high-speed relay may be referred to as a "hi" relay in diagnostic charts.

High-speed relay is located in air intake unit. This relay receives a signal from auto amplifier (system control panel) to operate blower motor at high speed. (Scheme 3)

INTAKE DOOR MOTOR

Intake door motor is attached to heater unit. This door rotates so air is drawn from inlets set by the auto amplifier (system control panel). Motor rotation is transferred to a lever that moves intake door. (Scheme 3)

INTAKE SENSOR

Intake sensor is located in evaporator housing. After air passes through evaporator, intake sensor detects air temperature, and converts this into a resistance value. Resistance is then sent to auto amplifier (system control panel). (Scheme 3)

IN-VEHICLE TEMPERATURE SENSOR

In-vehicle temperature sensor is mounted in instrument panel, to right of steering wheel, near radio. Passenger compartment air is drawn through an aspirator. In-vehicle sensor converts temperature variations to a resistance value. Resistance value is then sent to auto amplifier (system control panel). (Scheme 3)

MODE DOOR MOTOR

Mode door motor is attached to heater unit. This motor rotates so air is discharged from outlet(s) according to auto amplifier (system control panel) setting. Motor rotation is transferred to a link that moves the mode door. (Scheme 3)

POTENTIOMETER BALANCE RESISTOR (PBR)

Note. The potentiometer balance resistor may be referred to as a "potentio" balance resistor in diagnostic charts.

This variable resistor converts power servo value (air mix door position) into a resistance value. PBR inputs voltage that varies according to change in resistance value into auto amplifier (system control panel).

POTENTIOMETER TEMPERATURE CONTROL

Note. Potentiometer temperature control may be referred to as a "potentio" temperature control in diagnostic charts.

Potentiometer Temperature Control (PTC) is built into auto amplifier (system control panel). Temperature can be set in 1°F increments. Temperature is digitally displayed.

SUNLOAD SENSOR

The sunload sensor is located on right defroster grille. (Scheme 3) It detects sunload using a photo diode. This sunload is converted into a current value, which is input into auto amplifier (system control panel).

If auto amplifier detects an abrupt change in sunload through the sunload sensor, sunload input process will vary input to auto amplifier for approximately 38 seconds to prevent an unpleasant change in A/C operation.

HEATER CONTROL VALVE

Water cock/heater control valve lever is linked to the air mix door shaft so that amount of coolant flowing to heater core is a function of the air mix door aperture.

Scheme 3

AIR MIX DOOR

1. Install air mix door motor onto heater unit. Connect body harness. Access Code 41. See «SELF-DIAGNOSIS STEP 4»(ref-35301-S29510138372001010900000) under TROUBLE SHOOTING. Moving air mix door lever by hand, hold door in full cold position. Attach air mix door lever to rod holder. (Scheme 4)
2. Ensure air mix door is in correct position when accessing Codes 41-46. See «SELF-DIAGNOSIS STEP 4»(ref-35301-S29510138372001010900000) under TROUBLE SHOOTING.

Scheme 4

INTAKE DOOR

1. Install intake door motor on intake unit. Plug in harness connector. Access Code 41. See «SELF-DIAGNOSIS STEP 4»(ref-35301-S29510138372001010900000) under TROUBLE SHOOTING. Moving intake door link by hand, hold intake door in recirculate position. Attach the intake door lever to the rod holder. (Scheme 5)
2. Ensure intake door is in correct position when accessing Codes 41-46. See «SELF-DIAGNOSIS STEP 4»(ref-35301-S29510138372001010900000) under TROUBLE SHOOTING.

Scheme 5

MODE DOOR

1. Install mode door motor. Connect wiring harness. Access Code 41. See «SELF-DIAGNOSIS STEP 4»(ref-35301-S29510138372001010900000) under TROUBLE SHOOTING. Moving side link by hand, hold mode door in vent position. Attach mode door motor rod to side link rod holder. (Scheme 6)
2. Ensure mode door is in correct position when accessing Codes 41-46. See «SELF-DIAGNOSIS STEP 4»(ref-35301-S29510138372001010900000) under TROUBLE SHOOTING.

Scheme 6

Preliminary Information

1. Read «ENTERING/EXITING SELF-DIAGNOSTICS»(ref-35301-S42556658442001010900000) .
2. Perform PRELIMINARY CHECK for appropriate vehicle symptom. See TROUBLE SHOOTING - DIAGNOSTIC PROCEDURE charts in this article. PRELIMINARY CHECK charts will direct technician to either SELF-DIAGNOSIS or appropriate DIAGNOSTIC PROCEDURE chart(s).
3. Perform appropriate SELF-DIAGNOSIS step under TROUBLE SHOOTING or perform appropriate DIAGNOSTIC PROCEDURE. See TROUBLE SHOOTING - DIAGNOSTIC PROCEDURE charts in this article.

Checks LEDs & Segments

To proceed with self-diagnostic step 1, set temperature switch to "A" position. When self-diagnosis mode is entered, all Light Emitting Diodes (LEDs) and fluorescent display tubes should illuminate. (Scheme 2) Repair or replace if necessary.

Checks Sensor Circuits For Open/Short Circuits

1. With system in self-diagnosis step 1, set temperature switch to "B" position on auto amplifier (system control panel) to enter SELF-DIAGNOSIS STEP 2. Fluorescent display will illuminate a "2". If all sensor circuits are okay, display will change to "20". It may take as long as 4 seconds to check all sensor circuits.
2. If a sensor circuit is faulty, circuit code number will flash on display. Shorted circuit will have a flashing "-" in front of the number 2. Open circuit will NOT have a flashing "-". For example, if number "21" is displayed on auto amplifier ("2" will stay lit, and "1" will flash on and off), an open circuit is indicated.
3. If 2 sensor circuits are faulty, each code number will flash twice. To interpret codes, see «SELF-DIAGNOSIS STEP 2 CODE»(ref-35301-S12490596602001010900000) EXPLANATIONS table.

SELF-DIAGNOSIS STEP 2 CODE EXPLANATIONS

Checks Mode Door Position

1. With system in self-diagnosis step 2, set temperature switch to "C" position on auto amplifier to enter «SELF-DIAGNOSIS STEP»(ref-35301-S00050892872001010900000) 3. Fluorescent display will illuminate a "3". If all doors are in good order, display will change to "30". It may take as long as 16-20 seconds to check all doors.
2. If a door is faulty, it will be identified by another number illuminated to the right of "3". If 2 doors are faulty, each code number will blink twice. To interpret codes, see «SELF-DIAGNOSIS»(ref-35301-S37667943362001010900000) STEP 3 CODE EXPLANATIONS table.

Note. If any mode door motor position switch is malfunctioning, mode door motor also will malfunction.

SELF-DIAGNOSIS STEP 3 CODE EXPLANATIONS

Checks Temperature Detected By Sensors

1. With system in self-diagnosis step 4, set temperature switch to "E" position on auto amplifier to enter «SELF-DIAGNOSIS STEP»(ref-35301-S00293680512001010900000) 5. Fluorescent display will illuminate a "5". When defrost button is pressed once, fluorescent display will show temperature detected by intake sensor.
2. Press defrost button again; fluorescent display will show temperature detected by in-vehicle sensor. Press defrost button again; fluorescent display will show temperature detected by intake sensor.
3. Press defrost button again; fluorescent display again will illuminate "5". If temperature shown on fluorescent display differs greatly from actual temperature, inspect sensor circuit. If sensor circuit is okay, go to «TESTING»(ref-35301-S34613981692001010900000) .

Temperature Setting Trimmer

1. Temperature setting trimmer compensates for small differences between temperature setting (fluorescent display) and temperature felt by passengers in a range of plus or minus 6°F.
2. With system in SELF-DIAGNOSIS STEP 5, press fan button to enter auxiliary mode. Press UP or DOWN arrow buttons as desired. Each time an arrow button is pressed, temperature will change 1°F on fluorescent display. If vehicle battery is disconnected, temperature setting goes to 0°F.

Preliminary Check 1 Air Outlet Does Not Change. Scheme 7

Preliminary Check 2 Intake Door Does Not Change. Scheme 8

Preliminary Check 3 Insufficient Cooling. Scheme 9

Preliminary Check 4 Insufficient Heating. Scheme 10

Preliminary Check 5 Blower Motor Malfunction. Scheme 11

Preliminary Check 6 Magnet Clutch Does Not Engage. Scheme 12

Preliminary Check 7 Discharged Air Temperature Does Not Change. Scheme 13

Preliminary Check 8 Noise. Scheme 14

Diagnostic Procedure 1 Self-Diagnosis Cannot Be Performed. Scheme 15

Diagnostic Procedure 2 Ambient Temperature Sensor Circuit Open. Scheme 16

Diagnostic Procedure 3 In-Vehicle Temperature Sensor Circuit Open. Scheme 17

Diagnostic Procedure 4 Thermal Transmitter Circuit Open. Scheme 18

Diagnostic Procedure 5 Intake Sensor Circuit Open. Scheme 19

Diagnostic Procedure 6 Sunload Sensor Circuit Open. Scheme 20

Diagnostic Procedure 7 Potentiometer Balance Resistor Circuit Open. Scheme 21

Diagnostic Procedure 8 Ambient Temperature Sensor Circuit Shorted. Scheme 22

Diagnostic Procedure 9 In-Vehicle Temperature Sensor Circuit Shorted. Scheme 23

Diagnostic Procedure 11 Intake Sensor Circuit Shorted. Scheme 24

Diagnostic Procedure 12 Sunload Sensor Circuit Shorted. Scheme 25

Diagnostic Procedure 13 Potentiometer Balance Resistor Circuit Shorted. Scheme 26

Diagnostic Procedure 14 (1 Of 2) Mode Door Motor Does Not Operate Normally. Scheme 27

Diagnostic Procedure 14 (2 Of 2) Mode Door Motor Does Not Operate Normally. Scheme 28

Diagnostic Procedure 15 (1 Of 2) Intake Door Motor Does Not Operate Normally. Scheme 29

Diagnostic Procedure 15 (2 Of 2) Intake Door Motor Does Not Operate Normally. Scheme 30

Diagnostic Procedure 16 Air Mix Door Motor Does Not Operate Normally. Scheme 31

Diagnostic Procedure 17 (1 Of 3) Blower Motor Operation Is Malfunctioning. Scheme 32

Diagnostic Procedure 17 (2 Of 3) Blower Motor Operation Is Malfunctioning. Scheme 33

Diagnostic Procedure 17 (3 Of 3) Blower Motor Operation Is Malfunctioning. Scheme 34

Diagnostic Procedure 18 (1 Of 3) Magnet Clutch Does Not Engage. Scheme 35

Diagnostic Procedure 18 (2 Of 3) Magnet Clutch Does Not Engage. Scheme 36

Diagnostic Procedure 18 (3 Of 3) Magnet Clutch Does Not Engage. Scheme 37

Diagnostic Procedure 19 Maximum Cold Door Does Not Operate Normally. Scheme 38

A/C SYSTEM PERFORMANCE

1. Park vehicle out of direct sunlight. Ensure condenser and radiator are free of obstructions. Close all doors, but leave a window open. Open engine hood. Turn A/C switch to AUTO position. Set temperature setting to maximum cold position, mode switch to vent position and fan switch to highest speed.
2. Start engine and run it at 1500 RPM. Record ambient temperature and check outlet air temperature at center instrument panel vent after A/C system has run for about 10 minutes. See applicable «A/C SYSTEM PERFORMANCE SPECIFICATIONS»(ref-35301-S17309439482001010900000) table.

A/C SYSTEM PERFORMANCE SPECIFICATIONS

A/C, CONDENSER FAN & HIGH-SPEED RELAY

Remove relay from vehicle. Apply 12 volts to coil side of relay. Check for continuity between 2 remaining relay terminals. (Scheme 39) If continuity does not exist, replace relay.

Scheme 39

Turn ignition off. Disconnect the underhood ambient temperature sensor connector. (Scheme 3) Using an ohmmeter, measure resistance between harness terminals. Refer to the AMBIENT TEMPERATURE SENSOR, IN-VEHICLE SENSOR RESISTANCE table. If resistance is not as specified, replace sensor.

AMBIENT TEMPERATURE SENSOR, IN-VEHICLE SENSOR RESISTANCE

Power Supply Check

Ensure ignition is off. Disconnect auto amplifier (system control panel) connector. Turn ignition on. Connect voltmeter, in turn, between ground and following auto amplifier terminals: No. 1, No. 2 and No. 3. For terminal identification, see WIRING DIAGRAMS . Voltage should be 12 volts at each terminal. Repair if necessary. If malfunction still exists after performing proper trouble shooting procedures and ensuring voltage readings are okay, replace auto amplifier.

Ground Circuit Check

Ensure ignition is off. Disconnect auto amplifier connector. Connect an ohmmeter between auto amplifier connector terminal No. 8 and ground. For terminal identification, see WIRING DIAGRAMS . Continuity should exist. Repair if necessary. If voltage readings are okay but malfunction still exists, replace auto amplifier.

TRIPLE-PRESSURE SWITCH

Using an ohmmeter, check triple-pressure switch operation. See TRIPLE-PRESSURE SWITCH SPECIFICATIONS table. If switch does not test as specified, replace switch.

TRIPLE-PRESSURE SWITCH SPECIFICATIONS

Turn ignition off. Disconnect underdash in-vehicle sensor connector. (Scheme 3) Using an ohmmeter, measure resistance between harness terminals. See AMBIENT TEMPERATURE SENSOR, IN-VEHICLE SENSOR table under AMBIENT TEMPERATURE SENSOR. If resistance is not as specified, replace sensor.

Turn ignition off. Disconnect underdash intake sensor connector. (Scheme 4) Using an ohmmeter, measure resistance between harness terminals. See INTAKE SENSOR RESISTANCE table. If resistance is not as specified, replace sensor.

INTAKE SENSOR RESISTANCE

1. Turn ignition off. Using a voltmeter, measure voltage between the auto amplifier connector terminal No. 46 and ground. (Scheme 40) This will measure output voltage. To vary voltage reading, apply direct sunlight to sensor, and then shield sensor.
2. To measure input of sunload sensor to auto amplifier (system control panel), disconnect sensor from vehicle harness. Connect an ammeter between sensor connector terminals. To vary current reading, apply direct sunlight to sensor, and then shield sensor. See «SUNLOAD SENSOR SPECIFICATIONS»(ref-35301-S25456478482001010900000) table. If sensor does not test as specified, replace sensor.

SUNLOAD SENSOR SPECIFICATIONS

Scheme 40

THERMOSWITCH

Using an ohmmeter, check the thermoswitch operation. See THERMOSWITCH SPECIFICATIONS table. Replace thermoswitch if it does not test as specified.

THERMOSWITCH SPECIFICATIONS

1. Turn ignition on. With air mix door motor connected, measure voltage between terminals No. 34 and 48. (Scheme 41)
2. As air mix door motor moves from full cold to full hot position, voltmeter should indicate voltage slowly rising to 5 volts. PBR is located inside air mix door motor.

Scheme 41

A/C-HEATER COMPONENTS & DUCTS

Note. Removal and installation information is not available from manufacturer. Use (Scheme 3), see scheme 42 and (Scheme 42) as guides.

Scheme 42

Automatic A/C-Heater System Wiring Diagram (1 Of 2). Scheme 43

Automatic A/C-Heater System Wiring Diagram (2 Of 2). Scheme 44