A/c-Heater System - Automatic: Other Toyota 4Runner III

SYSTEM CONTROLS

A/C-heater control assembly consists of a liquid crystal display, temperature control knob and various buttons. All are used to activate A/C-heater system, set desired temperature, direct discharged air to appropriate outlets, activate rear defogger, control fan speed and check outside air temperature. (Scheme 6)

Scheme 6

WATER VALVE CONTROL CABLE

Set control lever to cool position. Remove cable retaining clip. Ensure water valve control cable is in full cool position. Install cable retaining clip.

Indicator Check

1. While pressing and holding AUTO and fresh/recirculated air switches simultaneously, turn ignition on. (Scheme 6) Indicators will flash on and off at one second intervals 4 times in succession. Press OFF button to cancel indicator check. After indicator check is complete, system will enter self-diagnostic mode.
2. Stored trouble codes will appear in sequence on temperature display panel. See «AUTOMATIC A/C-HEATER SYSTEM TROUBLE CODES»(ref-374-S11770572862000030800000) table. Press front defrost switch to display codes one at a time. Press OFF button to exit self-diagnostics.

AUTOMATIC A/C-HEATER SYSTEM TROUBLE CODES

CLEARING CODES

Remove ECU-B fuse from fuse block, located in driver's side fuse box, for 10 seconds or longer. After reinstalling fuse, ensure only normal code (Code 00) appears.

ACTUATOR CHECK

1. Perform «INDICATOR CHECK»(ref-374-S02282797372000030800000) under RETRIEVING CODES. When system enters self-diagnostic mode, press fresh/recirculated air switch. Every mode damper, motor and relay will operate at one-second intervals. Press front defrost switch to display codes one at a time and to step through checks one at a time.
2. Check airflow and temperature by hand. Each code is associated with a system operating condition. see scheme 1 Press OFF button to cancel actuator check mode.

Scheme 7

CODE 11: IN-VEHICLE (ROOM) TEMPERATURE SENSOR CIRCUIT

1. Remove A/C control assembly, leaving harness connectors connected. See «A/C CONTROL ASSEMBLY»(ref-374-S41050283762000030800000) under REMOVAL & INSTALLATION. Turn ignition on. Backprobe between terminals A30-4 (Black/Yellow wire) and A31-1 (Gray wire) at A/C control assembly harness connector. (Scheme 8)
2. Measure voltage while heating sensor. See «IN-VEHICLE (ROOM) TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-374-S33915736662000030800000) table.
3. If voltage is not as specified, test in-vehicle (room) temperature sensor. See «IN-VEHICLE TEMPERATURE SENSOR»(ref-374-S15829791242000030800000) under TESTING. Replace sensor if it is defective. If sensor is okay, go to next step.
4. Inspect wiring harness and connectors between sensor and A/C control assembly. Repair harness and connectors as necessary. If wiring harness and connectors are okay, temporarily substitute known-good A/C control assembly and retest system.

IN-VEHICLE (ROOM) TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS

Scheme 8

CODE 12: AMBIENT (OUTSIDE) TEMPERATURE SENSOR CIRCUIT

1. Remove A/C control assembly, leaving harness connectors connected. See «A/C CONTROL ASSEMBLY»(ref-374-S41050283762000030800000) under REMOVAL & INSTALLATION. Turn ignition on. Backprobe between terminals A30-3 (Black/Blue wire) and A31-1 (Gray wire) at A/C control assembly harness connector. (Scheme 8)
2. Measure voltage while heating outside (ambient) temperature sensor. See «AMBIENT (OUTSIDE) TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-374-S02890151932000030800000) table.
3. If voltage is not as specified, test sensor. See «AMBIENT TEMPERATURE SENSOR»(ref-374-S17038058002000030800000) under TESTING. Replace sensor if it is defective. If sensor is okay, go to next step.
4. Inspect wiring harness and connectors between sensor and A/C control assembly. Repair harness and connectors as necessary. If wiring harness and connectors are okay, temporarily substitute a known-good A/C control assembly and retest system.

AMBIENT (OUTSIDE) TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS

CODE 13: EVAPORATOR TEMPERATURE SENSOR CIRCUIT

1. Remove A/C control assembly, leaving harness connectors connected. See «A/C CONTROL ASSEMBLY»(ref-374-S41050283762000030800000) under REMOVAL & INSTALLATION. Turn ignition on. Backprobe between terminals A30-6 (White/Red wire) and A31-1 (Gray wire) at A/C control assembly harness connector. (Scheme 8)
2. Measure evaporator temperature sensor voltage at the temperatures specified. See «EVAPORATOR TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-374-S39175592442000030800000) table.
3. If voltage is not as specified, test evaporator temperature sensor. See «EVAPORATOR TEMPERATURE SENSOR»(ref-374-S19522679992000030800000) under TESTING. Replace sensor if it is defective. If sensor is okay, go to next step.
4. Inspect wiring harness and connectors between sensor and A/C control assembly. Repair harness and connectors as necessary. If wiring harness and connectors are okay, temporarily substitute a known-good A/C control assembly. Retest system.

EVAPORATOR TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS

CODE 14: ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT

1. Remove A/C control assembly, leaving harness connectors connected. See «A/C CONTROL ASSEMBLY»(ref-374-S41050283762000030800000) under REMOVAL & INSTALLATION. Turn ignition on. Backprobe between terminals A31-5 (Black/Red wire) and A31-1 (Gray wire) at A/C control assembly harness connector. (Scheme 8) Measure sensor voltage. See «ENGINE COOLANT (WATER) TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-374-S11318514882000030800000) table.
2. If voltage is not as specified, test engine coolant temperature sensor. See «ENGINE COOLANT TEMPERATURE SENSOR»(ref-374-S09107382442000030800000) under TESTING. Replace sensor if it is defective. If sensor is okay, go to next step.
3. Inspect wiring harness and connectors between sensor and A/C control assembly. Repair as necessary. If wiring harness and connectors are okay, temporarily substitute known-good A/C control assembly. Retest system.

ENGINE COOLANT (WATER) TEMPERATURE SENSOR CIRCUIT VOLTAGE SPECIFICATIONS

CODE 21: SOLAR SENSOR CIRCUIT

Note. If testing is done in a dark area, Code 21 may occur even though system is normal. Shine a light at solar sensor and recheck for Code 21.

1. Remove A/C control assembly, leaving harness connectors connected. See «A/C CONTROL ASSEMBLY»(ref-374-S41050283762000030800000) under REMOVAL & INSTALLATION. Turn ignition on. Backprobe between terminals A30-11 (Yellow wire) and A31-5 (Pink wire) at A/C control assembly harness connector. (Scheme 8) Measure sensor voltage. See «SOLAR SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-374-S20881264792000030800000) table.
2. If voltage is not as specified, test solar sensor. See «SOLAR SENSOR»(ref-374-S38930592252000030800000) under TESTING. Replace sensor if it is defective. If sensor is okay, go to next step.
3. Inspect wiring harness and connectors between sensor and A/C control assembly. Repair as necessary. If wiring harness and connectors are okay, temporarily substitute known-good A/C control assembly and retest system.

SOLAR SENSOR CIRCUIT VOLTAGE SPECIFICATIONS

CODE 23: PRESSURE SWITCH CIRCUIT

1. Remove A/C control assembly, leaving harness connectors connected. See «A/C CONTROL ASSEMBLY»(ref-374-S41050283762000030800000) under REMOVAL & INSTALLATION. Install manifold gauge set. Turn ignition on. Backprobe between terminal A30-9 (Orange wire) at A/C control assembly harness connector and ground. (Scheme 8)
2. Start engine. Turn A/C on. Pressure switch operation should be as specified. (Scheme 9) If pressure switch operation is not as specified, go to next step. If pressure switch operation is as specified, circuit is okay.
3. Unplug pressure switch connector, located on receiver/drier. Test for continuity between switch terminals at refrigerant pressures specified. (Scheme 10) Replace pressure switch if operation is not as specified. If switch is okay, inspect wiring harness and connectors between switch and A/C control assembly. If wiring harness and connectors are okay, substitute known-good A/C control assembly. Retest system.

Scheme 9

Scheme 10

CODE 31 OR 41: AIR MIX DAMPER POSITION SENSOR/SERVOMOTOR CIRCUIT

Note. For Code 41, see CODE 41: AIR MIX SERVOMOTOR CIRCUIT for additional trouble shooting procedures.

1. Remove A/C control assembly, leaving harness connectors connected. See «A/C CONTROL ASSEMBLY»(ref-374-S41050283762000030800000) under REMOVAL & INSTALLATION. Turn ignition on. Backprobe between terminals A30-8 (Black wire) and A31-1 (Gray wire) at A/C control assembly harness connector. (Scheme 8)
2. Measure sensor voltage while changing set temperature to activate air mix damper. See «AIR MIX DAMPER POSITION SENSOR CIRCUIT VOLTAGE»(ref-374-S08772378642000030800000) table.
3. If voltage is not as specified, test air mix servomotor. See «AIR MIX SERVOMOTOR»(ref-374-S10903594492000030800000) under TESTING. Replace servomotor if it is defective. If servomotor is okay, go to next step.
4. Inspect wiring harness and connectors between sensor and A/C control assembly. Repair as necessary. If wiring harness and connectors are okay, temporarily substitute known-good A/C control assembly. Retest system.

AIR MIX DAMPER POSITION SENSOR CIRCUIT VOLTAGE

CODE 32 OR 42: AIR INLET DAMPER POSITION SENSOR/SERVOMOTOR CIRCUIT

Note. For Code 42, see CODE 42: AIR INLET SERVOMOTOR CIRCUIT for additional trouble shooting procedures.

1. Remove A/C control assembly, leaving harness connectors connected. See «A/C CONTROL ASSEMBLY»(ref-374-S41050283762000030800000) under REMOVAL & INSTALLATION. Turn ignition on. Backprobe between terminals A31-7 (Yellow/Blue wire) and A30-1 (Gray wire) at A/C control assembly harness connector. (Scheme 8)
2. Measure sensor voltage while alternately pressing fresh air and recirculated air buttons to activate air inlet damper. See «AIR INLET DAMPER POSITION CIRCUIT VOLTAGE SPECIFICATIONS»(ref-374-S22615279262000030800000) table.
3. If voltage is not as specified, test air inlet servomotor. See «AIR INLET SERVOMOTOR»(ref-374-S40679617352000030800000) under TESTING. Replace servomotor if it is defective. If servomotor is okay, go to next step.
4. Inspect wiring harness and connectors between sensor and A/C control assembly. Repair as necessary. If wiring harness and connectors are okay, temporarily substitute known-good A/C control assembly. Retest system.

AIR INLET DAMPER POSITION CIRCUIT VOLTAGE SPECIFICATIONS

CODE 41: AIR MIX SERVOMOTOR CIRCUIT

Note. See CODE 31 OR 41: AIR MIX DAMPER POSITION SENSOR/SERVOMOTOR CIRCUIT for additional trouble shooting procedures.

1. Warm engine to normal operating temperature. Perform «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-374-S36654136012000030800000) . After system enters self-diagnostic mode, perform «ACTUATOR CHECK.»(ref-374-S20239456602000030800000)
2. Press DEF switch and check operation of air mix damper and blower condition. See «AIR MIX DAMPER AIRFLOW»(ref-374-S24062978432000030800000) table. Air mix damper operation should be as specified.
3. If air mix damper operates as specified, circuit is okay. If air mix damper does not operate as specified, see «AIR MIX SERVOMOTOR FUNCTIONAL CHECK»(ref-374-S06945097562000030800000) .

AIR MIX DAMPER AIRFLOW

Air Mix Servomotor Functional Check

1. Remove air mix servomotor. See «AIR MIX SERVOMOTOR»(ref-374-S15740043012000030800000) under REMOVAL & INSTALLATION. Unplug air mix servomotor connector.
2. Apply battery voltage to servomotor connector terminal No. 2 (Red wire). (Scheme 11) Connect terminal No. 4 (White wire) to ground. Air mix servomotor lever should move to cool position. Transpose battery and ground leads. Servomotor lever should move to hot position.
3. Replace air mix servomotor if it does not function as specified. If operation is as specified, inspect wiring harness and connectors between servomotor and A/C control assembly. Repair as necessary. If wiring harness and connectors are okay, substitute known-good A/C control assembly and retest system.

Scheme 11

CODE 42: AIR INLET SERVOMOTOR CIRCUIT

Note. See CODE 32 OR 42: AIR INLET DAMPER POSITION SENSOR/SERVOMOTOR CIRCUIT for additional trouble shooting procedures.

1. Remove glove box. Perform «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-374-S36654136012000030800000) . After system enters self-diagnostic mode, perform «ACTUATOR CHECK»(ref-374-S20239456602000030800000) .
2. Press DEF button to enter step mode and display codes. See «AIR INLET DAMPER AIRFLOW»(ref-374-S41465275852000030800000) table. Air inlet damper operation should be as specified.
3. If air inlet damper functions as specified, circuit is okay. If air inlet damper does not function as specified, test air inlet servomotor. See «AIR INLET SERVOMOTOR FUNCTIONAL CHECK»(ref-374-S26152047702000030800000) .

AIR INLET DAMPER AIRFLOW

Air Inlet Servomotor Functional Check

1. Remove air inlet servomotor. See «AIR INLET SERVOMOTOR»(ref-374-S40679617352000030800000) under REMOVAL & INSTALLATION. Unplug air inlet servomotor connector.
2. Connect battery voltage to air inlet servomotor connector terminal No. 1. (Scheme 12) Connect terminal No. 2 to ground. Air inlet servomotor lever should move to recirculated air (REC) position. Transpose battery and ground leads. Air inlet servomotor lever should move to fresh air (FRS) position.
3. Replace air inlet servomotor if it does not operate as specified. If servomotor operates correctly, inspect wiring harness and connectors between servomotor and A/C control assembly. Repair as necessary. If wiring harness and connectors are okay, substitute known-good A/C control assembly and retest system.

Scheme 12

AIR INLET SERVOMOTOR

1. Unplug air inlet servomotor connector. See «AIR INLET SERVOMOTOR»(ref-374-S11683283192000030800000) under REMOVAL & INSTALLATION. Measure resistance between servomotor connector terminals No. 4 and 5. (Scheme 12) If resistance is 4200-7800 ohms, go to next step. If resistance is not as specified, replace air inlet servomotor.
2. Connect ohmmeter between terminals No. 3 and 5. Connect battery voltage to terminal No. 1. Connect terminal No. 2 to ground. Transpose battery and ground leads. Resistance should be as specified for each damper position. See «AIR INLET DAMPER POSITION RESISTANCE SPECIFICATIONS»(ref-374-S29071107612000030800000) table.

AIR INLET DAMPER POSITION RESISTANCE SPECIFICATIONS

AIR MIX SERVOMOTOR

1. Remove air mix servomotor. See «AIR MIX SERVOMOTOR»(ref-374-S15740043012000030800000) under REMOVAL & INSTALLATION. Unplug air mix servomotor connector. Measure resistance between servomotor connector terminals No. 6 (Yellow wire) and No. 5 (Green wire). (Scheme 11) If resistance is 4800-7200 ohms, go to next step. If resistance is not as specified, replace air mix servomotor.
2. Connect ohmmeter between servomotor terminals No. 7 (Black wire) and No. 5 (Green wire). Connect air mix servomotor terminal No. 2 (Red wire) to battery voltage. (Scheme 11) Connect terminal No. 4 (White wire) to ground. Transpose battery and ground leads. Resistance should be as specified for each damper position. See «AIR MIX DAMPER POSITION RESISTANCE SPECIFICATIONS»(ref-374-S11439269232000030800000) table.

AIR MIX DAMPER POSITION RESISTANCE SPECIFICATIONS

AIR OUTLET SERVOMOTOR CIRCUIT

1. Warm engine to normal operating temperature. Perform «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-374-S36654136012000030800000) under SELF-DIAGNOSTICS. After system enters self-diagnostic mode, perform «ACTUATOR CHECK»(ref-374-S20239456602000030800000) .
2. Press front defrost switch to enter step mode and display codes. See «AIR OUTLET DAMPER AIRFLOW»(ref-374-S19297322762000030800000) table. Air outlet damper operation should be as specified.
3. If air outlet damper servomotor functions as specified, circuit is okay. If air outlet damper does not function as specified, test air outlet servomotor. See «AIR OUTLET SERVOMOTOR FUNCTIONAL TEST»(ref-374-S05328912552000030800000) .

AIR OUTLET DAMPER AIRFLOW

AMBIENT TEMPERATURE SENSOR

1. Unplug temperature sensor, located behind grille. Measure sensor resistance while heating sensor. See «AMBIENT TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS»(ref-374-S21830895082000030800000) table.
2. If resistance is not as specified, replace sensor. If resistance is within specification, check wiring harness and connectors between sensor and A/C control assembly. Repair harness and connectors as necessary. If wiring harness and connectors are okay, substitute known-good A/C control assembly. Retest system.

AMBIENT TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS

BACK-UP POWER CIRCUIT

1. Turn ignition off. Inspect ECU-B fuse in driver's side fuse box. If fuse is okay, go to next step. If fuse is blown, check for short and repair as necessary. See «WIRING DIAGRAMS»(ref-374-S03227353802000030800000).
2. Remove A/C control assembly, leaving harness connectors connected. Turn ignition on. Backprobe between A/C control assembly connector terminal A31-13 (Blue/Red wire) and ground. (Scheme 8) If battery voltage does not exist, repair White/Red wire between connector and ECU-B fuse.

BLOWER MOTOR CIRCUIT

1. Turn ignition off. Remove blower motor. Connect battery voltage to terminal No. 2 (Blue/Red wire) of blower motor. Connect terminal No. 1 (White/Blue wire) to ground. If blower motor runs smoothly, go to next step. Replace blower motor if it does not run smoothly.
2. Inspect wiring between blower motor and battery, and between blower motor and ground. Repair wiring as necessary.

BLOWER MOTOR LINEAR CONTROLLER

1. Remove blower motor linear controller, located in evaporator assembly lower right side. Disconnect harness connector. Turn ignition on.
2. Using DVOM, measure continuity between blower motor linear controller harness terminal No. 1 (White/Black wire) and ground. Continuity should exist. Measure voltage between blower motor linear controller harness terminal No. 3 (Blue/Red wire) and ground. Battery voltage should exist. If operation is not as specified, go to next step. If operation is as specified, substitute known-good blower motor linear controller. Retest system.
3. Turn ignition off. Reconnect blower motor linear controller harness connector. Turn ignition on. Measure voltage between blower motor linear controller terminal No. 4 (White/Blue wire) and ground. If operation is not as specified, check and repair appropriate wire(s) in circuit. See «WIRING DIAGRAMS»(ref-374-S03227353802000030800000) . If operation is as specified, substitute known-good blower motor linear controller. Retest system.

COMPRESSOR CIRCUIT

1. Turn ignition on. Inspect GAUGE fuse in driver's side fuse box. If fuse is okay, go next step. If fuse is blown, correct cause and replace fuse.
2. Turn ignition off. Remove A/C control assembly, leaving harness connectors connected. See «A/C CONTROL ASSEMBLY»(ref-374-S41050283762000030800000) under REMOVAL & INSTALLATION. Start and run engine at idle. Backprobe between A/C control assembly connector terminal A30-2 (Green/Black wire) and ground. (Scheme 8)
3. Press A/C control panel AUTO button. Voltmeter should indicate less than one volt. Press A/C control panel OFF button. Voltmeter should indicate battery voltage. If operation is as specified, go to next step. If operation is as not as specified, go to step 8.
4. Remove compressor clutch relay. Measure resistance between terminals No. 1 and 4. (Scheme 13) Resistance should be 62.5-90.9 ohms. Test for continuity between terminals No. 7 and 9. Continuity should exist. If relay operates as specified, go to next step. Replace relay if it does not operate as specified.
5. Connect battery voltage to terminal No. 1 of relay. Connect terminal No. 4 to ground. Test for continuity between terminals No. 1 and 9. Continuity should exist. If relay operates as specified, go to next step. Replace relay if it does not operate as specified.
6. Unplug connector from compressor clutch. Connect battery voltage to compressor clutch connector terminal. If clutch engages, go to next step. If clutch does not engage, repair or replace compressor clutch.
7. Inspect wiring and connectors associated with compressor relay and compressor. Repair or replace wiring and connectors as necessary.
8. Turn ignition off. Unplug connector A30 from A/C control assembly. (Scheme 8) Turn ignition on. Check for voltage at harness connector terminal A30-13 (Blue/Yellow wire). If battery voltage exists, go to next step. If battery voltage does not exist, substitute known-good Engine Control Module (ECM). Retest system.
9. Turn ignition off and reconnect wiring to A/C control assembly. Using a DVOM, backprobe between terminal A30-13 (Blue/Yellow wire) of A/C control assembly connector and ground. (Scheme 8) Start engine. Cycle A/C system on and off by pressing A/C control panel AUTO button. With compressor clutch engaged, voltmeter should indicate less than one volt. With compressor clutch disengaged, voltmeter should indicate battery voltage. If voltages are as specified, go to next step. If voltages are not as specified, substitute known-good A/C control assembly. Retest system.
10. Using a DVOM, backprobe between terminal A30-10 (Blue/Black wire) of A/C control assembly connector and ground. Start engine. Cycle AUTO switch on and off by pressing A/C button. With A/C system off, voltmeter should indicate less than 1.5 volts. With A/C system on, voltmeter should indicate battery voltage. If voltages are not as specified, go to next step. If voltages are as specified, substitute known-good A/C control assembly. Retest system.
11. Inspect wiring and connectors between A/C control assembly and ECM. Repair as necessary. If wiring harnesses and connectors are okay, go to next step.
12. Turn ignition off. Remove glove box. Unplug connectors from ECM. Turn ignition on. Press AUTO switch to turn system on. Measure voltage between ECM 28-pin connector E12, terminal No. 13 (Blue/Black wire) on ECM and ground.
13. With A/C switch on, 10-14 volts should exist. With A/C switch off, less than 1.5 volts should exist. If voltage is not as specified, temporarily substitute known-good A/C control assembly, and retest. If voltage is as specified, temporarily substitute known-good ECM. Retest system.

Scheme 13

ENGINE COOLANT TEMPERATURE SENSOR

Remove engine coolant temperature sensor, located at heater core. Place sensor and thermometer in water. Measure resistance between sensor terminals as water is heated. See ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS table. If resistance is not as specified, replace engine coolant temperature sensor.

ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS

EVAPORATOR TEMPERATURE SENSOR

Remove evaporator temperature sensor, located at evaporator. Measure sensor resistance at temperatures specified. See EVAPORATOR TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS table. If resistance is not as specified, replace sensor.

EVAPORATOR TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS

EXTRA-HI SPEED BLOWER RELAY

1. Check that continuity exists between relay terminals No. 3 and 4. (Scheme 14) If continuity does not exist, replace relay. If continuity exists, go to next step.
2. Apply battery voltage between terminals No. 3 and 4. Check for continuity between terminals No. 1 and 2. (Scheme 14) If continuity exists, relay is okay. If continuity does not exist, replace relay.

Scheme 14

Scheme 15

1. Turn ignition on. Inspect HEATER fuse, in fuse block in engine compartment. If fuse is okay, go next step. If fuse is blown, correct cause and replace fuse.
2. Remove A/C control assembly, leaving harness connectors connected. Turn ignition off. Check for voltage between A/C control assembly connector terminal A31-10 (Yellow/Red wire) and ground. (Scheme 8) If battery voltage exists, go to next step. If battery voltage does not exist, turn ignition on. Battery voltage should exist with blower motor on. If operation is not as specified, repair open or short in Yellow/Red wire between connector and heater main relay. If operation is as specified, system is okay.
3. Remove heater main relay, located behind glove box, on right side. Test for continuity between terminals No. 1 and 4. (Scheme 15) Continuity should not exist. Test for continuity between terminals No. 2 and 4. Continuity should exist. Measure resistance between terminals No. 3 and 5. Resistance should be 62.5-90.9 ohms.
4. Connect battery voltage to terminal No. 3, and connect terminal No. 5 to ground. Test for continuity between terminals No. 1 and 2. Continuity should exist. Test for continuity between terminals No. 2 and 4. Continuity should not exist. Replace relay if operation is not as specified. If relay operation is as specified, repair wiring between A/C control assembly connector and battery.

IGNITION POWER & GROUND CIRCUITS

1. Turn ignition on. Inspect GAUGE fuse, in driver's side fuse box. If fuse is okay, go next step. If fuse is blown, correct cause and replace fuse.
2. Remove console upper panel. Remove A/C control assembly, leaving harness connectors connected. Turn ignition on. Using DVOM, backprobe between connector terminals A31-26 (Black/Yellow wire) and A31-14 (White/Black wire). (Scheme 8) If battery voltage does not exist, go to next step. If battery voltage exists, circuit is okay.
3. Measure resistance between terminal A30-14 (White/Black wire) and ground. If resistance is less than one ohm, wire is okay. Repair open in White/Black wire if resistance is not less than one ohm.

IN-VEHICLE TEMPERATURE SENSOR

Remove in-vehicle temperature sensor. see scheme 1 Measure sensor resistance while heating sensor. See IN-VEHICLE TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS table. If resistance is not as specified, replace sensor.

IN-VEHICLE TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS

SOLAR SENSOR

Remove solar sensor from top of instrument panel. Unplug harness connector. Cover sensor with cloth. Measure resistance between sensor terminals. Remove cloth. Subject sensor to bright light. Measure resistance between sensor terminals. See SOLAR SENSOR RESISTANCE SPECIFICATIONS table. If resistance is not as specified, replace sensor.

SOLAR SENSOR RESISTANCE SPECIFICATIONS