Automatic A/c-Heater Systems: Diagnosis Lexus LX J100

SELF-DIAGNOSTICS

An Electronic Control Unit (ECU) within A/C control panel monitors system circuits and stores diagnostic trouble codes in memory if problems are detected. All codes, except DTC 22, are stored in memory. A malfunction is current if DTC 22 is displayed. To retrieve stored codes, see RETRIEVING DIAGNOSTIC TROUBLE CODES. Codes are displayed at temperature display (without navigation system) or on navigation display screen temperature display (with navigation system). see scheme 2or see scheme 3.

CLEARING DIAGNOSTIC TROUBLE CODES

Turn ignition off. Remove CIGAR fuse from underhood junction block. Wait a minimum of 10 seconds before reinstalling CIGAR fuse. DTCs will be cleared from memory. Recheck for DTCs. If only DTC 00 (system normal) exists, repair is complete.

DTC 11: FRONT IN-VEHICLE AIR TEMPERATURE SENSOR CIRCUIT

1. Remove A/C ECU, with connectors still connected. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION. Turn ignition on.
2. On vehicles without navigation system, backprobe and measure voltage between A/C ECU connector terminals C10-2 (Black wire) and C10-12 (Yellow/Green wire). see scheme 10 See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. On vehicles with navigation system, backprobe and measure voltage between A/C ECU connector terminals C25-10 (Black wire) and C25-1 (Yellow/Green wire). see scheme 11and see scheme 12. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
4. See «IN-VEHICLE TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-98895-S15188639732001072300000) table. If voltage is not as specified, check front in-vehicle air temperature sensor. See «IN-VEHICLE AIR TEMPERATURE SENSOR»(ref-98895-S34721671552001072300000) under COMPONENT TESTS. Replace in-vehicle air temperature sensor as necessary.
5. If in-vehicle air temperature sensor is okay, check for intermittent or poor connections between in-vehicle air temperature sensor and A/C ECU. If wiring harness and connections are okay, temporarily substitute a known-good A/C ECU, then retest system.

IN-VEHICLE TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS

DTC 12: AMBIENT AIR TEMPERATURE SENSOR CIRCUIT

1. Remove A/C ECU, with connectors still connected. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION. Turn ignition on.
2. On vehicles without navigation system, backprobe and measure voltage between A/C ECU connector terminals C10-3 (Blue/Yellow wire) and C10-12 (Yellow/Green wire). see scheme 10 See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. On vehicles with navigation system, backprobe and measure voltage between A/C ECU connector terminals C25-3 (Blue/Yellow wire) and C25-1 (Yellow/Green wire). see scheme 11and see scheme 12. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
4. See «AMBIENT TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-98895-S22359688442001072300000) table. If voltage is not as specified, check ambient air temperature sensor. See «AMBIENT AIR TEMPERATURE SENSOR»(ref-98895-S04127555512001072300000) under COMPONENT TESTS. Replace ambient air temperature sensor as necessary.
5. If ambient air temperature sensor is okay, check for intermittent or poor connections between ambient air temperature sensor and A/C ECU. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000). If wiring harness and connections are okay, temporarily substitute a known-good A/C ECU, then retest system.

AMBIENT TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS

DTC 13: FRONT EVAPORATOR TEMPERATURE SENSOR CIRCUIT

1. Remove A/C ECU, with connectors still connected. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION. Turn ignition on.
2. On vehicles without navigation system, backprobe and measure voltage between A/C ECU connector terminals C10-4 (Gray/Black wire) and C10-12 (Yellow/Green wire). see scheme 10 See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. On vehicles with navigation system, backprobe and measure voltage between A/C ECU connector terminals C25-11 (Gray/Black wire) and C25-1 (Yellow/Green wire). see scheme 11and see scheme 12. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
4. See «FRONT EVAPORATOR TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-98895-S31507499422001072300000) table. If voltage is not as specified, check evaporator temperature sensor. See «EVAPORATOR TEMPERATURE SENSOR»(ref-98895-S08001757122001072300000) under COMPONENT TESTS. Replace front evaporator temperature sensor as necessary.
5. If evaporator temperature sensor is okay, check for intermittent or poor connections between evaporator temperature sensor and A/C ECU. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000). If wiring harness and connections are okay, temporarily substitute a known-good A/C ECU, then retest system.

FRONT EVAPORATOR TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS

DTC 14: ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT

1. Remove A/C ECU, with connectors still connected. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION. Turn ignition on.
2. Without navigation system, backprobe and measure voltage between A/C ECU connector terminals C8-9 (Yellow/Black wire) and C11-22 (White/Black wire). see scheme 10 See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. With navigation system, backprobe and measure voltage between A/C ECU connector terminals C26-7 (Yellow/Black wire) and C26-11 (White/Black wire). see scheme 11and see scheme 12. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
4. See «ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-98895-S30255973442001072500000) table. If voltage is as specified, go to next step. If voltage is not as specified, check wiring harness for intermittent or poor connections between ECM and A/C ECU. Repair as necessary. If circuit is okay, replace A/C ECU and retest system.
5. Using scan tool and a thermometer, compare coolant temperature sensor reading with actual operating coolant temperature. A reading of -40°F (-40°C) indicates an open circuit in harness between ECM and ECT sensor. A reading of 284°F (140°C) indicates a short circuit in harness between ECM and ECT sensor.
6. Repair harness as necessary. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000). If harness is okay, check ECT sensor. See «ENGINE COOLANT TEMPERATURE SENSOR»(ref-98895-S15644094102001072500000) under COMPONENT TESTS.

ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS

DTC 17: REAR EVAPORATOR TEMPERATURE SENSOR CIRCUIT

1. Remove rear A/C amplifier, with connectors still connected. See «REAR COOLING UNIT»(ref-98895-S31098752402001060500000) under REMOVAL & INSTALLATION. Turn ignition on.
2. Backprobe and measure voltage between connector terminals A33-7 (Yellow wire) and A33-9 (Yellow/Green wire). see scheme 13 See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. See «REAR EVAPORATOR TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-98895-S42471525102001072700000) table. If voltage is not as specified, go to next step. If voltage is as specified, check rear evaporator temperature sensor. See «REAR EVAPORATOR TEMPERATURE SENSOR»(ref-98895-S23080718232001072700000) under COMPONENT TESTS. Replace sensor as necessary.
4. Check for intermittent or poor connections between rear in-vehicle temperature sensor and rear A/C amplifier connectors. Repair as necessary. If circuits are okay, replace rear A/C amplifier.

REAR EVAPORATOR TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS

DTC 18: EXHAUST GAS SENSOR CIRCUIT

Note. Exhaust gas sensor resistance decreases when sensor is exposed to exhaust gas.

1. Remove A/C ECU, with connectors still connected. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION. Turn ignition on.
2. Without navigation system, backprobe and measure voltage between A/C ECU connector terminals C10-10 (Yellow wire) and C10-12 (Yellow/Green wire). see scheme 10 See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. With navigation system, backprobe and measure voltage between A/C ECU connector terminals C25-12 (Yellow wire) and C25-1 (Yellow/Green wire). see scheme 11and see scheme 12. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
4. If voltage is 1.0-4.5 volts at 50-95°F (10-35°C), replace A/C ECU and retest system. If voltage is 1.0-4.5 volts at 50-95°F (10-35°C), check exhaust gas sensor. See «EXHAUST GAS SENSOR»(ref-98895-S37617356442001072400000) under COMPONENT TESTS. Replace sensor as necessary.
5. Check wiring harness and connectors between sensor and A/C ECU. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000). Repair as necessary. If wiring harness and connectors are okay, temporarily substitute a known-good A/C ECU, then retest system.

DTC 19: REAR IN-VEHICLE AIR TEMPERATURE SENSOR CIRCUIT

1. Remove rear A/C amplifier, with connectors still connected. See «REAR COOLING UNIT»(ref-98895-S31098752402001060500000) under REMOVAL & INSTALLATION. Turn ignition on.
2. Backprobe and measure voltage between connector terminals A35-12 (Green/Yellow wire) and A35-7 (Black wire). see scheme 13 See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. See «REAR IN-VEHICLE AIR TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-98895-S29430118472001072700000) table. If voltage is not as specified, go to next step. If voltage is as specified, check rear in-vehicle air temperature sensor. See «REAR IN-VEHICLE TEMPERATURE SENSOR»(ref-98895-S32828894122001072700000) under COMPONENT TESTS. Replace sensor as necessary.
4. Check for intermittent or poor connections between rear in-vehicle temperature sensor and rear A/C amplifier connectors. Repair as necessary. If circuits are okay, replace rear A/C amplifier.

REAR IN-VEHICLE AIR TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS

DTC 21: SOLAR SENSOR CIRCUIT

Note. If testing is done in a dark area, DTC may set even though system is normal. Shine a bright light at solar sensor and recheck for DTC.

1. Remove A/C ECU, with connectors still connected. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION. Turn ignition on.
2. Without navigation system, backprobe and measure voltage between A/C ECU connector terminals C10-6 (Black/Yellow wire) and C10-1 (Green/Red wire). see scheme 10 See «SOLAR SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-98895-S10337857642001072000000) table. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. With navigation system, backprobe and measure voltage between A/C ECU connector terminals C25-2 (Black/Yellow wire) and C25-9 (Green/Red wire). see scheme 11and see scheme 12. See «SOLAR SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-98895-S10337857642001072000000) table. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
4. If voltage is as specified, go to next step. If voltage is not as specified, check solar sensor. See «SOLAR SENSOR»(ref-98895-S12275116372001072000000) under COMPONENT TESTS. Replace sensor as necessary.
5. Check wiring harness and connectors between sensor and A/C ECU. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000). Repair as necessary. If wiring harness and connectors are okay, temporarily substitute a known-good A/C ECU, then retest system.

SOLAR SENSOR CIRCUIT VOLTAGE SPECIFICATIONS

DTC 22: COMPRESSOR LOCK SENSOR

1. Remove A/C ECU, with connectors still connected. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION. Start engine and allow to idle. Turn A/C on.
2. Without navigation system, backprobe and measure voltage between A/C ECU connector terminals C8-7 (White/Blue wire) and C10-12 (Yellow/Green wire). see scheme 10 See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. With navigation system, backprobe and measure voltage between A/C ECU connector terminals C27-15 (White/Blue wire) and C25-1 (Yellow/Green wire). see scheme 11and see scheme 12. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
4. If voltage is 10-14 volts, go to next step. If voltage is not 10-14 volts, check for intermittent or poor connections at compressor lock sensor and A/C ECU connectors. Repair as necessary. If circuits are okay, replace sensor and A/C ECU.
5. Raise and support vehicle. Disconnect compressor lock sensor. Measure resistance between compressor lock sensor terminals No. 1 and 2. (Scheme 22) See «COMPRESSOR LOCK SENSOR RESISTANCE»(ref-98895-S34146621642001072700000) table. If resistance is not as specified, replace compressor and lock sensor as an assembly.

COMPRESSOR LOCK SENSOR RESISTANCE

Scheme 22

DTC 23: REFRIGERANT PRESSURE SENSOR CIRCUIT

1. Remove A/C ECU, with connectors still connected. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION. Install A/C manifold gauge set.
2. Without navigation system, backprobe and measure voltage between A/C ECU connector terminal C8-10 (Blue/White wire) and connector terminal C11-22 (White/Black wire). see scheme 10 See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. With navigation system, backprobe and measure voltage between connector terminal C26-4 (Blue/White wire) and connector terminal C26-11 (White/Black wire). see scheme 11and see scheme 12. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
4. Start and operate engine at 1500 RPM. Press A/C button to ON position. As low-side pressure increases to more than 32.6 psi (2.3 kg/cm 2 ), voltage will change to zero. As low-side pressure decreases to less than 28.4 psi (2.0 kg/cm 2 ), voltage will change to battery voltage.
5. As high-side pressure increases to more than 455.4 psi (32.0 kg/cm 2 ) voltage will change to zero volts. As high-side pressure decreases to less than 369.8 psi (26.0 kg/cm 2 ) voltage will change to battery voltage.
6. If voltage changes as specified, no problem is indicated at this time. If voltage does not change as specified, check refrigerant pressure switch. See «REFRIGERANT PRESSURE SWITCH»(ref-98895-S22557922102001072100000) under COMPONENT TESTS. If pressure switch is okay, go to next step.
7. Check for intermittent or poor connections at pressure sensor and A/C ECU connectors. Repair as necessary. If circuits are okay, replace A/C ECU and retest system.

DTC 26: REAR INLET AIR TEMPERATURE SENSOR CIRCUIT

1. Remove rear A/C amplifier, with connectors still connected. See «REAR COOLING UNIT»(ref-98895-S31098752402001060500000) under REMOVAL & INSTALLATION. Turn ignition on.
2. Backprobe and measure voltage between A/C amplifier connector terminals A33-8 (Gray/Green wire) and A33-9 (Yellow/Green wire). see scheme 13 See «REAR INLET AIR TEMPERATURE SENSOR»(ref-98895-S21763910072001072700000) table.
3. If voltage is as specified, check rear A/C amplifier. See «REAR A/C AMPLIFIER»(ref-98895-S14713355932001060500000) under SYSTEM TESTS. Replace rear A/C amplifier as necessary.
4. If voltage is not as specified, check rear inlet air temperature sensor. See «REAR INLET AIR TEMPERATURE SENSOR»(ref-98895-S14672147062001072800000) under COMPONENT TESTS. Replace sensor as necessary. If sensor is okay, go to next step.
5. Check for intermittent or poor connections between rear inlet air temperature sensor and rear A/C amplifier connectors. Repair as necessary. If circuits are okay, replace rear A/C amplifier and retest system.

REAR INLET AIR TEMPERATURE SENSOR

DTC 31 & 41: FRONT AIR MIX DAMPER POSITION SENSOR CIRCUIT

1. Remove A/C ECU, with connectors still connected. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION. Turn ignition on. Change air temperature control to activate front air mix damper. Monitor voltage while damper is moving.
2. Without navigation system, backprobe and measure voltage between A/C ECU connector terminal C10-8 (Black/Yellow wire) and terminal C10-12 (Yellow/Green wire). see scheme 10 See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000). See «FRONT AIR MIX DAMPER POSITION SENSOR VOLTAGE»(ref-98895-S34274107132001072100000) table.
3. With navigation system, backprobe and measure voltage between A/C ECU connector terminal C25-5 (Black/Yellow wire) and terminal C25-1 (Yellow/Green wire). see scheme 11and see scheme 12. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000). See «FRONT AIR MIX DAMPER POSITION SENSOR VOLTAGE»(ref-98895-S34274107132001072100000) table.
4. If voltage is not as specified, check front air mix damper position sensor resistance. See «FRONT AIR MIX DAMPER CONTROL SERVOMOTOR POSITION SENSOR»(ref-98895-S31036635922001072100000) under COMPONENT TESTS.
5. Check for intermittent or poor connections at front air mix damper servomotor and rear A/C amplifier connectors. Repair as necessary. If connections are okay, replace A/C ECU and retest system.

FRONT AIR MIX DAMPER POSITION SENSOR VOLTAGE

DTC 32 & 42 : AIR INLET DAMPER POSITION SENSOR CIRCUIT

1. Remove A/C ECU, with connectors still connected. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION. Turn ignition on. Press recirculation/fresh air button to activate air inlet damper. Monitor voltage while damper is moving.
2. Without navigation system, backprobe and measure voltage between A/C ECU connector terminal C10-9 (Black/Yellow wire) and terminal C10-12 (Yellow/Green wire). see scheme 10 See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000). See «AIR INLET DAMPER POSITION SENSOR VOLTAGE»(ref-98895-S21137400572001072300000) table.
3. With navigation system, backprobe and measure voltage between A/C ECU connector terminal C25-13 (Black/Yellow wire) and terminal C25-1 (Yellow/Green wire). see scheme 11and see scheme 12. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000). See «AIR INLET DAMPER POSITION SENSOR VOLTAGE»(ref-98895-S21137400572001072300000) table.
4. If voltage is as specified, go to next step. If voltage is not as specified, check air inlet damper position sensor resistance. See «AIR INLET DAMPER POSITION SENSOR»(ref-98895-S37357884642001072300000) under COMPONENT TESTS.
5. Check for intermittent or poor connections at air inlet damper servomotor and rear A/C amplifier connectors. Repair as necessary. If connections are okay, replace A/C ECU and retest system.

AIR INLET DAMPER POSITION SENSOR VOLTAGE

Scheme 23

DTC 37 & 47: REAR AIR MIX DAMPER POSITION SENSOR CIRCUIT

1. Remove rear A/C amplifier, with connectors still connected. See «REAR A/C AMPLIFIER»(ref-98895-S26530626342001072600000) under REMOVAL & INSTALLATION. Turn ignition on. Change rear air temperature control from maximum cool to maximum hot positions. Monitor voltage while damper is moving.
2. Backprobe and measure voltage between connector terminal A33-6 (Gray/Red wire) and terminal A33-9 (Yellow/Green wire). see scheme 13 See «REAR AIR MIX DAMPER POSITION SENSOR VOLTAGE»(ref-98895-S39357325072001072600000) table.
3. If voltage is as specified, go to next step. If voltage is not as specified, check rear air mix damper position sensor resistance. See «REAR AIR MIX DAMPER CONTROL SERVOMOTOR POSITION SENSOR»(ref-98895-S20013731922001072600000) under COMPONENT TESTS.
4. Check for intermittent or poor connections at rear air mix damper servomotor and rear A/C amplifier connectors. Repair as necessary. If connections are okay, replace A/C ECU and retest system.

REAR AIR MIX DAMPER POSITION SENSOR VOLTAGE

DTC 41: FRONT AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT

Note. For front air mix damper position sensor circuit, see DTC 31 & 41: FRONT AIR MIX DAMPER POSITION SENSOR CIRCUIT .

1. If equipped with navigation system, go to next step. If not equipped with navigation system, check servomotor operation. See «FRONT AIR MIX DAMPER CONTROL SERVOMOTOR»(ref-98895-S30278464872001072100000) under COMPONENT TESTS. Replace front air mix damper control servomotor as necessary.
2. If equipped with navigation system, warm engine to normal operating temperature and allow to idle. Activate actuator check mode. See «ACTUATOR CHECK»(ref-98895-S42162457782001060500000) under SELF-DIAGNOSTICS. After system enters self-diagnostic mode, press A/C switch button and check air mix damper and blower motor operation. See «AIR MIX DAMPER AIRFLOW»(ref-98895-S23725686372001072300000) table.
3. If air mix damper and blower motor operation is not as specified, check servomotor operation. See «FRONT AIR MIX DAMPER CONTROL SERVOMOTOR»(ref-98895-S30278464872001072100000) under COMPONENT TESTS. Replace front air mix damper control servomotor as necessary.
4. Check wiring harness and connectors between servomotor and A/C ECU. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000) . Repair as necessary. If wiring harness and connectors are okay, temporarily substitute a known-good A/C ECU, then retest system.

AIR MIX DAMPER AIRFLOW

DTC 42: AIR INLET DAMPER CONTROL SERVOMOTOR CIRCUIT

Note. For air inlet damper position sensor circuit, see DTC 32 & 42 : AIR INLET DAMPER POSITION SENSOR CIRCUIT .

1. If equipped with navigation system, go to next step. If not equipped with navigation system, check servomotor operation. See «AIR INLET DAMPER CONTROL SERVOMOTOR»(ref-98895-S01557862162001072300000) under COMPONENT TESTS. Replace air inlet damper control servomotor as necessary.
2. If equipped with navigation system, start engine and allow to idle at normal operating temperature. Activate actuator check mode. See «ACTUATOR CHECK»(ref-98895-S42162457782001060500000) under SELF-DIAGNOSTICS. After system enters self-diagnostic mode, press A/C switch button and check air inlet damper and blower motor operation. See «AIR INLET DAMPER AIRFLOW»(ref-98895-S09367079722001072400000) table.
3. If air mix damper and blower motor operation is not as specified, check servomotor operation. See «FRONT AIR MIX DAMPER CONTROL SERVOMOTOR»(ref-98895-S30278464872001072100000) under COMPONENT TESTS. Replace front air inlet damper control servomotor as necessary.
4. Check for intermittent or poor connections at air inlet damper and rear A/C amplifier connectors. Repair as necessary. If circuit is okay, replace A/C ECU.

AIR INLET DAMPER AIRFLOW

DTC 47: REAR AIR MIX DAMPER CONTROL SERVOMOTOR

Note. For rear air mix damper control servomotor position sensor circuit, see DTC 37 & 47: REAR AIR MIX DAMPER POSITION SENSOR CIRCUIT .

1. If equipped with navigation system, go to next step. If not equipped with navigation system, check servomotor operation. See «REAR AIR MIX DAMPER CONTROL SERVOMOTOR»(ref-98895-S25419838552001072600000) under COMPONENT TESTS. Replace rear air mix damper control servomotor as necessary.
2. If equipped with navigation system, start engine and allow to idle at normal operating temperature. Activate actuator check mode. See «ACTUATOR CHECK»(ref-98895-S42162457782001060500000) under SELF-DIAGNOSTICS. After system enters self-diagnostic mode, press A/C switch button and check rear air mix damper and blower motor operation. See «REAR AIR MIX DAMPER AIRFLOW»(ref-98895-S38656595122001072600000) table.
3. If rear air mix damper and blower motor operation is not as specified, check servomotor operation. See «REAR AIR MIX DAMPER CONTROL SERVOMOTOR»(ref-98895-S25419838552001072600000) under COMPONENT TESTS. If rear air mix damper servomotor is okay, go to next step. Replace rear air mix damper control servomotor as necessary.
4. Check for intermittent or poor connections at rear air mix damper and rear A/C amplifier connectors. Repair as necessary. If circuit is okay, replace A/C amplifier.

REAR AIR MIX DAMPER AIRFLOW

Illumination Test (W/O Navigation System)

1. Remove A/C ECU control panel. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION. Using a fused jumper wire, connect battery voltage to A/C ECU connector terminal C11-10 (Green wire). Connect battery ground to A/C ECU connector terminal C11-11 (White/Green wire). see scheme 10
2. A/C ECU illumination bulbs should illuminate. Check bulbs that do not illuminate. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000). Check for continuity between bulb terminals. Replace bulb(s) as necessary. If bulb(s) are okay, replace A/C ECU.

Illumination Test (W/ Navigation System)

1. Remove A/C ECU control panel. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION. Using a fused jumper wire, connect battery voltage to A/C ECU connector terminal C24-9 (Green wire). Connect battery ground to A/C ECU connector terminal C24-20 (White/Green wire). see scheme 11and see scheme 12.
2. A/C ECU illumination bulbs should illuminate. Check bulbs that do not illuminate. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000). Check for continuity between bulb terminals. Replace bulb(s) as necessary. If bulb(s) are okay, replace A/C ECU.

Indicator Light Test

Using a fused jumper wire, connect battery voltage to A/C ECU connector terminal C11-1 (Red/Blue wire). see scheme 10 Connect battery ground to A/C ECU connector terminal C11-22 (White/Black wire). Depress all buttons and verify each indicator illuminates (if applicable). If one or more indicators does not illuminate, replace A/C control panel.

Using a fused jumper wire, connect battery voltage to A/C ECU connector terminal C24-10 (Red/Blue wire). see scheme 11and see scheme 12. Connect battery ground to A/C ECU connector terminal C24-8 (White/Black wire). Depress all buttons and verify each indicator illuminates (if applicable). If one or more indicators does not illuminate, replace A/C control panel.

Illumination Test

Using a fused jumper wire, connect battery voltage to rear A/C control panel terminal No. 8 (Green wire). Connect battery ground to rear A/C control panel terminal No. 11 (Green/White wire). (Scheme 24) Rear A/C control panel illumination should illuminate. If A/C control panel illumination does not illuminate, replace rear A/C control panel.

Using a fused jumper wire, connect battery voltage to rear A/C control panel terminal No. 9 (Blue/Red wire). Connect battery ground to specified rear A/C control panel terminal. See REAR A/C CONTROL PANEL INDICATOR LIGHT TERMINAL IDENTIFICATION table. (Scheme 24) See WIRING DIAGRAMS. Replace rear A/C control panel if any indicator does not illuminate.

REAR A/C CONTROL PANEL INDICATOR LIGHT TERMINAL IDENTIFICATION

Scheme 24

Switch Continuity Test

Using DVOM, measure continuity between specified terminals. See REAR A/C CONTROL PANEL SWITCH CONTINUITY SPECIFICATIONS table. (Scheme 24) See WIRING DIAGRAMS. Continuity should exist between specified terminals. If continuity does not exist as specified, replace rear A/C control panel and retest system.

REAR A/C CONTROL PANEL SWITCH CONTINUITY SPECIFICATIONS

Temperature Selector Variable Resistor Test

1. Measure resistance between rear A/C control panel terminals No. 20 (Green/Yellow wire) and No. 22 (Yellow/Red wire). If resistance is about 3000 ohms, go to next step. If resistance is not about 3000 ohms, replace rear A/C control panel. (Scheme 24) See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
2. Measure resistance between rear A/C control panel terminals No. 21 (Blue/Orange wire) and No. 22 (Yellow/Red wire). Slowly move temperature control lever from fully cool position to fully warm position. see scheme 4 If resistance does not change from zero ohms to about 3000 ohms, replace rear A/C control panel and recheck system.

Functional Test

1. Remove suspect power transistor. See «REAR POWER TRANSISTORS»(ref-98895-S29776419592001072600000) under REMOVAL & INSTALLATION. Using a fused jumper wire, connect battery voltage and a 3.4 watt test light in series to power transistor terminal No. 1. Connect battery ground to terminal No. 2. (Scheme 25)
2. Connect another 3.4 watt test light between battery voltage and power transistor terminal No. 4. If first test light illuminates, power transistor is okay. If first test light does not illuminate, replace power transistor.

Resistance test

Measure resistance between power transistor terminals No. 3 and 4. (Scheme 25) If resistance is 2000-2400 ohms, power transistor is okay. If resistance is not 2000-2400 ohms, replace power transistor.

Scheme 25