A/C-HEATER CONTROL PANEL
The A/C-heater control panel consists of a liquid crystal display, temperature control knob and various push buttons to activate A/C system, direct discharged air to desired vents, activate rear defogger, and control blower fan speed. (Scheme 15)
Scheme 15
Scheme 15: A/C-HEATER CONTROL PANEL
RETRIEVING CODES
- Simultaneously press and hold AUTO and recirculated air switches. (Scheme 15) Turn ignition on. All indicators will flash 4 times, at one-second intervals. Tone will sound when indicators flash.
- A/C system will enter self-diagnostic mode. To end indicator check, press and release OFF switch. Read codes at temperature display.
- If trouble code is displayed, proceed to appropriate trouble shooting procedure. See «DIAGNOSTIC CODE IDENTIFICATION»(ref-125180-S30260786842001100400000) table. Codes are displayed in ascending order. To slow rate at which codes are displayed, press fresh air button to change display to step operation. Each time fresh air button is pressed, display changes by one step.
- If tone sounds as code is displayed, problem currently exists. If tone does not sound as code is displayed, problem occurred in past and does not presently exist.
| Code | Diagnosis |
|---|
| 00 | Normal |
| 11 (1) | In-Vehicle Temperature Sensor Circuit |
| 12 (2) | Ambient Temperature Sensor Circuit |
| 13 | Evaporator Temperature Sensor Circuit |
| 14 | Coolant Temperature Sensor Circuit |
| 21 (3) | Solar Sensor Circuit |
| 22 (4) | Compressor Lock Sensor Circuit |
| 23 (4) | Pressure Switch Circuit |
| 31 | Air Mix Door Position Sensor Circuit |
| 32 | Air Inlet Door Position Sensor Circuit |
| 33 | Air Outlet Door Position Sensor Circuit |
| 41 | Air Mix Door Servomotor Circuit |
| 42 | Air Inlet Door Servomotor Circuit |
| 43 | Air Outlet Door Servomotor Circuit |
| (1) If in-vehicle temperature is -4°F (-20°C) or less, Code 11 may set even though system is normal. (2) If outside air temperature is -58°F (-50°C) or less, Code 12 may occur set though system is normal. (3) If testing is done in a dark area, Code 21 may set even though system is normal. Shine a light at solar sensor and recheck codes. (4) Malfunction is current. Code is not stored in memory. |
| (1) | If in-vehicle temperature is -4°F (-20°C) or less, Code 11 may set even though system is normal. |
| (2) | If outside air temperature is -58°F (-50°C) or less, Code 12 may occur set though system is normal. |
| (3) | If testing is done in a dark area, Code 21 may set even though system is normal. Shine a light at solar sensor and recheck codes. |
| (4) | Malfunction is current. Code is not stored in memory. |
DIAGNOSTIC CODE IDENTIFICATION
ACTUATOR CHECK
- Perform step 1) of «RETRIEVING CODES»(ref-125180-S15638380142001100400000). When system enters self-diagnostic mode, press recirculated air button. Each mode door, motor, and relay will operate at one-second intervals. Press fresh air button to display codes one at a time, and perform step-by-step actuator check.
- Check airflow and temperature by hand. Tone will sound each time display code changes. Each display code is associated with a system operating condition. (Scheme 16)or (Scheme 17). Press OFF button to cancel actuator check mode.
Scheme 16
Scheme 17
CLEARING CODES
Remove DOME fuse, located in relay box No. 2 on left side of engine compartment. Wait at least 10 seconds before installing fuse. Perform RETRIEVING CODES procedure to verify only Code 00 (normal) is displayed.
Voltage Check
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION.
- Turn ignition on. Backprobe between terminals A12-7 (Yellow/Blue wire) and A12-20 (Brown wire) of A/C-heater control panel connector. (Scheme 18)
- Measure voltage while heating in-vehicle temperature sensor. See «IN-VEHICLE TEMPERATURE SENSOR CIRCUIT VOLTAGE»(ref-125180-S08838651152001100400000) SPECIFICATIONS table.
- If voltage is as specified, temporarily substitute a known-good A/C-heater control panel, then retest system. If circuit voltage is not as specified, measure the sensor resistance. See «SENSOR RESISTANCE TEST»(ref-125180-S28428690002001100400000).
| Sensor Temperature °F (°C) | (1) Volts |
|---|
| 77 (25) | 1.8-2.2 |
| 104 (40) | 1.2-1.6 |
| (1) As temperature increases, voltage should gradually decrease. |
| (1) | As temperature increases, voltage should gradually decrease. |
IN-VEHICLE TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS
Scheme 18
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION.
- Turn ignition on. Backprobe between terminals A12-8 (Pink wire) and A12-20 (Brown wire) of A/C-heater control panel connector. (Scheme 18)
- Measure circuit voltage while heating ambient temperature sensor, located behind grille on lower right side. Refer to the «AMBIENT TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-125180-S39489774582001100400000) table.
- If voltage is as specified, temporarily substitute a known-good A/C-heater control panel, then retest system. If voltage is not as specified, measure ambient temperature sensor resistance. See «SENSOR RESISTANCE TEST»(ref-125180-S28428690002001100400000).
| Sensor Temperature °F (°C) | (1) Volts |
|---|
| 77 (25) | 1.35-1.75 |
| 104 (40) | 0.85-1.25 |
| (1) As temperature increases, voltage should gradually decrease. |
| (1) | As temperature increases, voltage should gradually decrease. |
AMBIENT TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION.
- Turn ignition on. Backprobe between terminals A12-9 (Blue/Yellow wire) and A12-20 (Brown wire) of A/C-heater control panel connector. (Scheme 18)
- Measure circuit voltage at specified temperatures. See «EVAPORATOR TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-125180-S34493032262001100400000) table.
- If voltage is as specified, temporarily substitute a known-good A/C-heater control panel, then retest system. If voltage is not as specified, measure the evaporator temperature sensor resistance. See «SENSOR RESISTANCE TEST»(ref-125180-S28428690002001100400000).
| Sensor Temperature °F (°C) | (1) Volts |
|---|
| 32 (0) | 2.0-2.4 |
| 59 (15) | 1.4-1.8 |
| (1) As temperature increases, voltage should gradually decrease. |
| (1) | As temperature increases, voltage should gradually decrease. |
EVAPORATOR TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION.
- Turn ignition on. Backprobe between terminals A12-10 (Light Green/Red wire) and A12-20 (Brown wire) of A/C-heater control panel connector. (Scheme 18)
- Measure circuit voltage at specified temperatures. See «COOLANT TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-125180-S29130662662001100400000) table.
- If voltage is as specified, temporarily substitute a known-good A/C-heater control panel, then retest system. If voltage is not as specified, test sensor resistance. See «SENSOR RESISTANCE TEST»(ref-125180-S28428690002001100400000).
| Sensor Temperature°F (°C) | (1) Volts |
|---|
| 32 (0) | 2.8-3.2 |
| 104 (40) | 1.8-2.2 |
| 158 (70) | 0.9-1.3 |
| (1) As temperature increases, voltage should gradually decrease. |
| (1) | As temperature increases, voltage should gradually decrease. |
COOLANT TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION.
- Turn ignition on. Backprobe between terminals A12-18 (Brown/White wire) and A12-11 (Yellow/Green wire) of A/C-heater control panel connector. (Scheme 18)
- Measure the circuit voltage at specified conditions. See «SOLAR SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-125180-S09452013692001100400000) table. If voltage is not as specified, test sensor resistance. See «SENSOR RESISTANCE TEST»(ref-125180-S28428690002001100400000). If voltage is within specification, temporarily substitute a known-good A/C-heater control panel, then retest system.
| Condition | (1) Volts |
|---|
| Sensor Covered By Cloth | 4.0-4.5 |
| Sensor Subjected To Bright Light | Less Than 4.0 |
| (1) As light intensity increases, voltage should decrease. |
| (1) | As light intensity increases, voltage should decrease. |
SOLAR SENSOR CIRCUIT VOLTAGE SPECIFICATIONS
Compressor Drive Belt Check
- Ensure drive belt fits properly on compressor pulley. If pointer is not in range "A" on tensioner scale, replace belt. (Scheme 19) If tension is okay, go to next step.
- Start engine. Turn blower and A/C on. Observe compressor. If compressor locks during operation, repair compressor. If compressor does not lock during operation, measure sensor resistance. Refer to the «SENSOR RESISTANCE TEST»(ref-125180-S28428690002001100400000).
Scheme 19
Pressure Switch Circuit Voltage Check
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION. Backprobe terminal A12-5 (Blue/Black wire) of A/C-heater control panel connector to ground. (Scheme 18)
- Connect manifold gauge set. Turn ignition and A/C on. Observe voltage and pressure. On low pressure side of system, voltage should switch from 12 volts to zero volts as pressure increases to more than 38 psi (2.0 kg/cm 2 ). On high pressure side of system, voltage should switch from zero volts to 12 volts as pressure increases to more than 455 psi (32 kg/cm 2 ).
- If voltage changes as specified, temporarily substitute a known-good A/C-heater control panel, then retest system. If voltage is not as specified, test pressure switch continuity. Proceed to the «PRESSURE SWITCH CONTINUITY CHECK»(ref-125180-S20919327802001100400000).
PRESSURE SWITCH CONTINUITY CHECK
- Unplug pressure switch connector, located in liquid line on right side of engine compartment. Turn ignition on. Check continuity between switch terminals while A/C system pressure changes.
- On low pressure side of system, switch should change from no continuity to continuity as system pressure increases to more than 33 psi (2.3 kg/cm 2 ). On high pressure side of system, switch should change from no continuity to continuity as pressure increases to more than 370 psi (26 6kg/cm 2 ). If continuity is not as specified, replace pressure switch.
- If continuity is as specified, inspect wiring harness and connectors between pressure switch and A/C-heater control panel. Repair as necessary. If wiring harness and connectors are okay, temporarily substitute a known-good A/C-heater control panel, then retest system.
CODE 31 OR 41: - AIR MIX DOOR POSITION SENSOR CIRCUIT
Note. For Code 41, also see CODE 41 - AIR MIX DOOR SERVOMOTOR CIRCUIT for additional trouble shooting procedures.
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL»(ref-125180-S27775115312001100400000) under REMOVAL & INSTALLATION.
- Turn ignition on. Backprobe between terminals A12-22 (Green/White 6wire) and A12-20 (Brown wire) of A/C-heater control panel connector. (Scheme 18)
- Measure voltage while changing set temperature to activate air mix 6door. See «AIR MIX DOOR POSITION SENSOR CIRCUIT VOLTAGE»(ref-125180-S04335470502001100400000) SPECIFICATIONS table.
- If voltage is as specified, temporarily substitute a known-good 6A/C-heater control panel, then retest system. If voltage is not as specified, measure sensor resistance. See «SENSOR RESISTANCE»(ref-125180-S28428690002001100400000) TEST.
| Set Temperature | (1) Volts |
|---|
| Maximum Cool | 3.70-4.27 |
| Maximum Hot | 0.88-1.16 |
| (1) As set temperature increases, voltage should gradually decrease. |
| (1) | As set temperature increases, voltage should gradually decrease. |
AIR MIX DOOR POSITION SENSOR CIRCUIT VOLTAGE SPECIFICATIONS
CODE 32 OR 42: - AIR INLET DOOR POSITION SENSOR CIRCUIT
Note. For Code 42, also see CODE 42 AIR INLET DOOR SERVOMOTOR CIRCUIT for additional trouble shooting procedures.
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION.
- Turn ignition on. Backprobe between terminals A12-23 (Gray wire) and A12-20 (Brown wire) of A/C-heater control panel connector. (Scheme 18)
- Measure voltage while alternately pressing fresh air and recirculated air switches to activate the air inlet door. Refer to the «AIR INLET DOOR POSITION SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-125180-S36205803732001100400000) table.
- If voltage is as specified, temporarily substitute a known-good A/C-heater control panel, then retest system. If voltage is not as specified, measure sensor resistance. See «SENSOR RESISTANCE»(ref-125180-S28428690002001100400000) TEST.
| Switch/Inlet Position | (1) Volts |
|---|
| Recirculated Air | 3.70-4.27 |
| Fresh Air | 0.88-1.16 |
| (1) Voltage should gradually decrease as air inlet door moves from recirculated air to fresh air position. |
| (1) | Voltage should gradually decrease as air inlet door moves from recirculated air to fresh air position. |
AIR INLET DOOR POSITION SENSOR CIRCUIT VOLTAGE SPECIFICATIONS
CODE 33 OR 43: - AIR OUTLET DOOR POSITION SENSOR CIRCUIT
Note. For Code 43, also see CODE 43 AIR OUTLET DOOR SERVOMOTOR CIRCUIT for additional trouble shooting procedures.
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION.
- Turn ignition on. Backprobe between terminals A12-25 (Yellow/Red wire) and A12-20 (Brown wire) of A/C-heater control panel connector. (Scheme 18)
- Measure voltage while pressing MODE switch to activate air outlet door servomotor. See «AIR OUTLET DOOR POSITION SENSOR CIRCUIT»(ref-125180-S18607225942001100400000) VOLTAGE SPECIFICATIONS table.
- If voltage is as specified, temporarily substitute a known-good A/C-heater control panel, then retest system. If voltage does not measure as specified, measure sensor resistance. Refer to the «SENSOR RESISTANCE TEST»(ref-125180-S28428690002001100400000).
| Position | (1) Volts |
|---|
| Face | 3.70-4.27 |
| Defrost | 0.88-1.16 |
| (1) Voltage should gradually decrease as air outlet door changes from face to defrost position. |
| (1) | Voltage should gradually decrease as air outlet door changes from face to defrost position. |
AIR OUTLET DOOR POSITION SENSOR CIRCUIT VOLTAGE SPECIFICATIONS
CODE 41: - AIR MIX DOOR SERVOMOTOR CIRCUIT
Note. Also see CODE 31 OR 41 - AIR MIX DOOR POSITION SENSOR CIRCUIT for additional trouble shooting procedures.
CODE 42: - AIR INLET DOOR SERVOMOTOR CIRCUIT
Note. Also see CODE 32 OR 42 AIR INLET DOOR POSITION SENSOR CIRCUIT for additional trouble shooting procedures.
CODE 43: - AIR OUTLET DOOR SERVOMOTOR CIRCUIT
Note. Also see CODE 33 OR 43 - AIR OUTLET DOOR POSITION SENSOR CIRCUIT for additional trouble shooting procedures.
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION. Turn ignition on. Backprobe between terminal A10-15 (Blue/Red wire) of A/C-heater control panel connector and ground. (Scheme 18)
- If battery voltage exists, temporarily substitute a known-good A/C-heater control panel, then retest system. If battery voltage does not exist, inspect CIG fuse. See CIG FUSE CHECK.
CIG Fuse Check
Inspect CIG fuse, located in fuse block No. 1, beneath instrument panel. If fuse is okay, inspect wiring between A/C-heater control panel and battery. Repair wiring as necessary. Replace fuse if blown, and then inspect for short circuit, and repair as necessary.
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION. Backprobe between terminal A10-1 (Red wire) of A/C-heater control panel connector and ground. (Scheme 18)
- If battery voltage exists, temporarily substitute a known-good A/C-heater control panel, then retest system. If battery voltage does not exist, inspect DOME fuse in junction block No. 2. If fuse is okay, inspect wiring and connectors between A/C-heater control panel and battery. Repair as necessary.
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION. Backprobe between terminal A11-8 (Black/Red wire) of A/C-heater control panel connector and ground. (Scheme 18)
- If 1-3 volts exist, temporarily substitute a known-good A/C-heater control panel, then retest system. If 1-3 volts does not exist, check blower motor operation. See BLOWER MOTOR CHECK below.
Blower Motor Check
- Remove blower motor. See «BLOWER MOTOR R & I»(ref-125180-S39392221352001100400000) under REMOVAL & INSTALLATION. Connect battery voltage to blower motor connector terminal No. 2 (Black/Red wire). Connect terminal No. 1 (Black wire) to ground.
- Blower motor should operate smoothly. If blower motor does not operate smoothly, replace blower motor. If blower motor operates smoothly, check blower motor control relay. See BLOWER MOTOR CONTROL RELAY CHECK below.
Blower Motor Control Relay Check
- Remove blower motor control relay, leaving harness connected. See «BLOWER MOTOR»(ref-125180-S22490574602001100400000) under REMOVAL & INSTALLATION. Turn ignition on, and blower motor on high speed. Check blower motor control relay between specified terminals, and compare values to chart. (Scheme 20)
- If values are not as specified, replace blower motor control relay. If values are as specified, inspect blower motor control relay wiring harness and connector. Repair as necessary.
Scheme 20
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION. Start engine.
- Press any fan speed switch. Backprobe terminal A12-2 (Blue/Yellow wire) of A/C-heater control panel connector to ground. (Scheme 18)
- Turn A/C system on. Battery voltage should exist. Turn A/C system off. Voltmeter should indicate less than one volt. If compressor circuit voltage is as specified, test A/C compressor clutch. See COMPRESSOR CLUTCH TEST below. If compressor circuit voltage is not as specified, measure compressor clutch circuit voltage. See COMPRESSOR CLUTCH VOLTAGE CHECK heading below.
Compressor Clutch Voltage Check
- Turn ignition on. Backprobe between terminal A11-4 (Blue/Red wire) of A/C-heater control panel connector and ground. (Scheme 18)
- With A/C system on, voltage should be less than one volt. Voltage should be 4-6 volts with A/C system off. If voltage is as specified, test compressor clutch relay. See COMPRESSOR CLUTCH RELAY CHECK below. If voltage is not as specified, go to next step.
- Turn ignition off. Unplug A/C-heater control panel connectors. Turn ignition on. Measure voltage between terminal A11-4 (Blue/Red wire) of A/C-heater control panel harness connector and ground.
- If voltage is 4-6 volts, temporarily substitute a known-good A/C-heater control panel, then retest system. If voltage is not 4-6 volts, go to next step.
- Inspect wiring and connectors between A/C-heater control panel and Electronic Control Module (ECM), located below passenger-side of instrument panel. Repair as necessary. If wiring harness and connectors are okay, temporarily substitute a known-good ECM, then retest system.
Compressor Clutch Relay Check
- Remove compressor clutch relay from relay block No. 2, located in engine compartment. Ensure continuity exists between terminals No. 1 and 2. (Scheme 21) Continuity should not exist between terminals No. 3 and 5.
- Apply battery voltage to relay terminal No. 1, and connect terminal No. 2 to ground. Continuity should exist between terminals No. 3 and 5. If continuity is not as specified, replace compressor clutch relay. If continuity is as specified, perform ENGINE CONTROL MODULE (ECM) CIRCUIT VOLTAGE CHECK below.
Scheme 21
Engine Control Module (ECM) Circuit Voltage Check
- Remove ECM, leaving harness connectors attached. ECM is located below passenger's side of instrument panel. Turn ignition on. Operate blower motor at high speed. Backprobe between terminal ACMG (White wire) of ECM connector and known-good ground. (Scheme 22)
- With A/C system on, voltage should be about 1.3 volts. With A/C system off, voltage should be between 1.3 volts and battery voltage. If voltage is not as specified, temporarily substitute known-good ECM, then retest system.
- If voltage is as specified, inspect wiring and connectors between ECM and A/C-heater control panel. Repair as necessary. If wiring and connectors are okay, temporarily substitute known-good A/C-heater control panel, then retest system.
Scheme 22
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION.
- Turn ignition on. Backprobe between terminal A11-9 (Blue/White wire) of A/C-heater control panel connector and ground. (Scheme 18) Turn ignition on. Measure voltage under conditions specified in «HEATER MAIN RELAY CIRCUIT SPECIFICATIONS»(ref-125180-S11964178302001100400000) table.
- If voltage is as specified, temporarily substitute a known-good A/C-heater control panel, then retest system. If voltage is not as specified, test heater main relay. See HEATER MAIN RELAY TEST heading below.
| Ignition Switch Position | Volts |
|---|
| OFF | 0 |
| ON |
| Blower On | 0 |
| Blower Off | Battery Voltage |
HEATER MAIN RELAY CIRCUIT SPECIFICATIONS
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION.
- Turn ignition on. Backprobe between terminals A10-6 (Red/Green wire) and A10-7 (White/Black wire) of A/C-heater control panel connector. (Scheme 18)
- If battery voltage exists, temporarily substitute a known-good A/C-heater control panel, then retest system. If battery voltage does not exist, go to GROUND WIRE CHECK below.
Ground Wire Check
Turn ignition off. Test for continuity between A/C-heater control panel connector terminal A10-7 (White/Black wire) and ground. (Scheme 18) If continuity exists, inspect heater fuse. See HTR FUSE CHECK below. If continuity does not exist, repair wiring between A/C-heater control panel connector terminal A10-7 and body ground.
HTR Fuse Check
Inspect HTR fuse in junction block No. 1, located beneath instrument panel. If fuse is okay, inspect harness and connectors between A/C-heater control panel and battery. Repair as necessary. If fuse is blown, replace fuse and inspect for short circuit.
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION. Start engine. Backprobe between terminal A11-3 (Black/Yellow wire) of A/C-heater control panel connector and ground. (Scheme 18)
- With temperature control knob set to maximum cold position, battery voltage should exist. With temperature control knob set to maximum heat position, voltage should be less than one volt. If voltage is as specified, no problem is indicated at this time. If voltage is not as specified, go to VACUUM SWITCHING VALVE (VSV) TEST.
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION. Turn ignition on. Backprobe between terminals A12-4 (Violet/White wire) and A12-20 (Brown wire) of A/C-heater control panel. (Scheme 18)
- Press AUTO control knob. With knob pressed, voltage should be less than one volt. With knob released, voltage should be 4-6 volts. If voltage is as specified, no problem is indicated at this time. If voltage is not as specified, go to next step.
- Turn ignition off. Unplug connector from automatic control switch. Connect ohmmeter between terminals No. 3 (Violet/White wire) and No. 4 (Brown wire) of automatic control switch. (Scheme 23) With AUTO switch pressed, continuity should exist. Continuity should not exist with switch released. If continuity is as specified, go to next step. Replace switch if continuity is not as specified.
- Inspect wiring and connectors between temperature control switch and A/C-heater control panel. Repair as necessary. If wiring harness and connectors are okay, temporarily substitute a known-good A/C-heater control panel, then retest system.
Scheme 23
Voltage Check (SC400)
- Remove A/C-heater control panel, leaving harness connectors attached. See «A/C-HEATER CONTROL PANEL R & I»(ref-125180-S07526538652001100400000) under REMOVAL & INSTALLATION. Turn ignition on. Backprobe between terminal A11-11 (Red/Green wire) of A/C-heater control panel connector and ground. (Scheme 18)
- Set temperature control knob to maximum cool position. Voltage should be less than one volt. Set temperature control knob to maximum heat position. Battery voltage should exist. If voltage is not as specified, go to next step. If voltage is as specified, no problem is indicated at this time.
- Turn ignition off. Unplug connectors from A/C-heater control panel. Turn ignition on. Measure voltage between terminal A11-11 (Red/Green wire) of A/C-heater control panel harness connector and ground. If battery voltage does not exist, go to next step. If battery voltage exists, temporarily substitute a known-good A/C-heater control panel, then retest system.
- Inspect wiring and connectors between cooling fan ECU and A/C-heater control panel. Cooling fan ECU is located behind A/C-heater control panel. Repair as necessary. If wiring and connectors are okay, temporarily substitute a known-good cooling fan ECU, then retest system.
