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

Front A/C Control Panel (Without Navigation System)

A/C functions are controlled by push-button controls, A/C AUTO switch, A/C on-off switch, and rotating temperature control knob. (Scheme 32) A/C ECU is located in center of instrument panel. A/C controls operate air supply selection (fresh or recirculated air), mode selection, temperature selection and blower motor speeds.

Scheme 32

Front A/C Control Panel (With Navigation System)

A/C functions are controlled by push-button controls, A/C AUTO switch, A/C on-off switch, temperature control button, and navigation display touch screen. (Scheme 33) A/C ECU is located in center of instrument panel. A/C controls operate air supply selection (fresh or recirculated air), mode selection, temperature selection and blower motor speeds.

Scheme 33

Rear A/C Control Panel

Functions of rear A/C are controlled by a separate control panel. (Scheme 34) By depressing the REAR button (located under A/C control panel), rear passengers can control rear A/C functions. Rear A/C control panel functions, controlled by push-buttons, are A/C AUTO, blower motor speed and mode operation. Temperature is selected using a sliding lever. Rear A/C control panel is located in rear overhead console.

Scheme 34

COMPRESSOR BELT TENSION

Ensure drive belt tension falls within "A" range of belt tensioner scale. (Scheme 35) If tension does not fall within "A" range, replace belt. When installing a new belt, belt tension indicator should be within "B" range of belt tensioner scale.

Scheme 35

FRONT A/C

Note. Perform FRONT A/C SYMPTOM TESTS in order listed.

A/C System Does Not Operate

1. Check A/C Electronic Control Unit (ECU). See «FRONT A/C ECU (W/O NAVIGATION SYSTEM)»(ref-98895-S41625521632001060500000) or «FRONT A/C ECU (W/ NAVIGATION SYSTEM)»(ref-98895-S30481195422001071600000) under SYSTEM TESTS.
2. Check ACC power source circuit. See «ACC POWER SOURCE CIRCUIT»(ref-98895-S02437621282001060500000) under SYSTEM TESTS.

No Blower Motor Control

1. Check blower motor circuit. See «BLOWER MOTOR CIRCUIT»(ref-98895-S32395191622001060500000) under SYSTEM TESTS.
2. Check A/C Electronic Control Unit (ECU). See «FRONT A/C ECU (W/O NAVIGATION SYSTEM)»(ref-98895-S41625521632001060500000) or «FRONT A/C ECU (W/ NAVIGATION SYSTEM)»(ref-98895-S30481195422001071600000) under SYSTEM TESTS.
3. Check solar sensor circuit. See «DTC 21: SOLAR SENSOR CIRCUIT»(ref-98895-S40225436832001060500000) under DIAGNOSTIC TESTS.
4. Check front blower motor control relay. See «RELAYS»(ref-98895-S31781469152001072000000) under COMPONENT TESTS.

Insufficient Airflow

1. Check blower motor circuit. See «BLOWER MOTOR CIRCUIT»(ref-98895-S32395191622001060500000) under SYSTEM TESTS.
2. Check front blower motor control relay. See «RELAYS»(ref-98895-S31781469152001072000000) under COMPONENT TESTS.

No Cool Air Comes Out

1. Ensure A/C system has proper refrigerant charge. See «A/C SYSTEM PERFORMANCE»(ref-98895-S39981270312001060500000) under SYSTEM TESTS. Correct refrigerant quantity as necessary.
2. Ensure drive belt tension is correct. See «COMPRESSOR BELT TENSION»(ref-98895-S17855320022001060500000) under ADJUSTMENTS. Replace drive belt as necessary.
3. Inspect A/C system performance. See «A/C SYSTEM PERFORMANCE»(ref-98895-S39981270312001060500000) under SYSTEM TESTS.
4. Check compressor magnetic clutch circuit. See «COMPRESSOR MAGNETIC CLUTCH CIRCUIT»(ref-98895-S15568180892001060500000) under SYSTEM TESTS.
5. Check pressure switch circuit. See «DTC 23: REFRIGERANT PRESSURE SENSOR CIRCUIT»(ref-98895-S10317629412001060500000) under DIAGNOSTIC TESTS.
6. Check front air mix damper position sensor circuit. See «DTC 31 & 41: FRONT AIR MIX DAMPER POSITION SENSOR CIRCUIT»(ref-98895-S26950678862001060500000) under DIAGNOSTIC TESTS.
7. Check front air mix damper control servomotor circuit. See «DTC 41: FRONT AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT»(ref-98895-S00664530632001060500000) under DIAGNOSTIC TESTS.
8. Check front in-vehicle temperature sensor circuit. See «DTC 11: FRONT IN-VEHICLE TEMPERATURE SENSOR CIRCUIT»(ref-98895-S15649091492001060500000) under DIAGNOSTIC TESTS.
9. Check ambient air temperature sensor circuit. See «DTC 12: AMBIENT AIR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S08305194542001060500000) under DIAGNOSTIC TESTS.
10. Check A/C Electronic Control Unit (ECU). See «FRONT A/C ECU (W/O NAVIGATION SYSTEM)»(ref-98895-S41625521632001060500000) or «FRONT A/C ECU (W/ NAVIGATION SYSTEM)»(ref-98895-S30481195422001071600000) under SYSTEM TESTS.

No Warm Air Comes Out

1. Check front air mix damper position sensor circuit. See «DTC 31 & 41: FRONT AIR MIX DAMPER POSITION SENSOR CIRCUIT»(ref-98895-S26950678862001060500000) under DIAGNOSTIC TESTS.
2. Check front air mix damper control servomotor circuit. See «DTC 41: FRONT AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT»(ref-98895-S00664530632001060500000) under DIAGNOSTIC TESTS.
3. Check front in-vehicle temperature sensor circuit. See «DTC 11: FRONT IN-VEHICLE TEMPERATURE SENSOR CIRCUIT»(ref-98895-S15649091492001060500000) under DIAGNOSTIC TESTS.
4. Check ambient air temperature sensor circuit. See «DTC 12: AMBIENT AIR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S08305194542001060500000) under DIAGNOSTIC TESTS.
5. Check front evaporator temperature sensor circuit. See «DTC 13: FRONT EVAPORATOR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S11610845272001060500000) under DIAGNOSTIC TESTS.
6. Check A/C Electronic Control Unit (ECU). See «FRONT A/C ECU (W/O NAVIGATION SYSTEM)»(ref-98895-S41625521632001060500000) or «FRONT A/C ECU (W/ NAVIGATION SYSTEM)»(ref-98895-S30481195422001071600000) under SYSTEM TESTS.

Output Air Is Warmer Or Cooler Than Set Temperature, Or Response Is Slow

1. Ensure A/C system has proper refrigerant charge. See «A/C SYSTEM PERFORMANCE»(ref-98895-S39981270312001060500000) under SYSTEM TESTS. Correct refrigerant quantity as necessary.
2. Ensure drive belt tension is correct. See «COMPRESSOR BELT TENSION»(ref-98895-S17855320022001060500000) under ADJUSTMENTS. Replace drive belt as necessary.
3. Inspect A/C system performance. See «A/C SYSTEM PERFORMANCE»(ref-98895-S39981270312001060500000) under SYSTEM TESTS.
4. Check electric condenser fan system. See «ELECTRIC CONDENSER FAN»(ref-98895-S31542622222001060500000) under COMPONENT TESTS.
5. Check solar sensor circuit. See «DTC 21: SOLAR SENSOR CIRCUIT»(ref-98895-S40225436832001060500000) under DIAGNOSTIC TESTS.
6. Check front in-vehicle temperature sensor circuit. See «DTC 11: FRONT IN-VEHICLE TEMPERATURE SENSOR CIRCUIT»(ref-98895-S15649091492001060500000) under DIAGNOSTIC TESTS.
7. Check ambient air temperature sensor circuit. See «DTC 12: AMBIENT AIR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S08305194542001060500000) under DIAGNOSTIC TESTS.
8. Check front evaporator temperature sensor circuit. See «DTC 13: FRONT EVAPORATOR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S11610845272001060500000) under DIAGNOSTIC TESTS.
9. Check front air mix damper position sensor circuit. See «DTC 31 & 41: FRONT AIR MIX DAMPER POSITION SENSOR CIRCUIT»(ref-98895-S26950678862001060500000) under DIAGNOSTIC TESTS.
10. Check front air mix damper control servomotor circuit. See «DTC 41: FRONT AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT»(ref-98895-S00664530632001060500000) under DIAGNOSTIC TESTS.
11. Check front air inlet damper position sensor circuit. See «DTC 32 & 42 : AIR INLET DAMPER POSITION SENSOR CIRCUIT»(ref-98895-S20008122142001060500000) under DIAGNOSTIC TESTS.
12. Check front air inlet damper control servomotor circuit. See «DTC 42: AIR INLET DAMPER CONTROL SERVOMOTOR CIRCUIT»(ref-98895-S10807154012001060500000) under DIAGNOSTIC TESTS.
13. Check condenser fins for blockage or damage. If fins are bent, straighten using a screwdriver or pliers. Check condenser and fittings for refrigerant leaks. Repair as necessary.
14. Check evaporator and fittings for refrigerant leaks.
15. Check heater core and fittings for coolant leaks.
16. Check expansion valve operation. See «EXPANSION VALVE»(ref-98895-S17853859232001060500000) under COMPONENT TESTS.
17. Check A/C Electronic Control Unit (ECU). See «FRONT A/C ECU (W/O NAVIGATION SYSTEM)»(ref-98895-S41625521632001060500000) or «FRONT A/C ECU (W/ NAVIGATION SYSTEM)»(ref-98895-S30481195422001071600000) under SYSTEM TESTS.

No Temperature Control (Only Maximum Cool Or Maximum Warm)

1. Check front in-vehicle temperature sensor circuit. See «DTC 11: FRONT IN-VEHICLE TEMPERATURE SENSOR CIRCUIT»(ref-98895-S15649091492001060500000) under DIAGNOSTIC TESTS.
2. Check ambient air temperature sensor circuit. See «DTC 12: AMBIENT AIR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S08305194542001060500000) under DIAGNOSTIC TESTS.
3. Check front air mix damper position sensor circuit. See «DTC 31 & 41: FRONT AIR MIX DAMPER POSITION SENSOR CIRCUIT»(ref-98895-S26950678862001060500000) under DIAGNOSTIC TESTS.
4. Check front air mix damper control servomotor circuit. See «DTC 41: FRONT AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT»(ref-98895-S00664530632001060500000) under DIAGNOSTIC TESTS.
5. Check A/C Electronic Control Unit (ECU). See «FRONT A/C ECU (W/O NAVIGATION SYSTEM)»(ref-98895-S41625521632001060500000) or «FRONT A/C ECU (W/ NAVIGATION SYSTEM)»(ref-98895-S30481195422001071600000) under SYSTEM TESTS.

No Inlet Air Control

1. Check front air inlet damper position sensor circuit. See «DTC 32 & 42 : AIR INLET DAMPER POSITION SENSOR CIRCUIT»(ref-98895-S20008122142001060500000) under DIAGNOSTIC TESTS.
2. Check front air inlet damper control servomotor circuit. See «DTC 42: AIR INLET DAMPER CONTROL SERVOMOTOR CIRCUIT»(ref-98895-S10807154012001060500000) under DIAGNOSTIC TESTS.
3. Check exhaust gas sensor circuit. See «DTC 18: EXHAUST GAS SENSOR CIRCUIT»(ref-98895-S20760626772001060500000) under DIAGNOSTIC TESTS.
4. Check A/C Electronic Control Unit (ECU). See «FRONT A/C ECU (W/O NAVIGATION SYSTEM)»(ref-98895-S41625521632001060500000) or «FRONT A/C ECU (W/ NAVIGATION SYSTEM)»(ref-98895-S30481195422001071600000) under SYSTEM TESTS.

No Airflow Control

1. Check air outlet (vent mode) servomotor operation. See «AIR OUTLET (VENT MODE) SERVOMOTOR»(ref-98895-S24155773152001060500000) under COMPONENT TESTS.
2. Check A/C Electronic Control Unit (ECU). See «FRONT A/C ECU (W/O NAVIGATION SYSTEM)»(ref-98895-S41625521632001060500000) or «FRONT A/C ECU (W/ NAVIGATION SYSTEM)»(ref-98895-S30481195422001071600000) under SYSTEM TESTS.

REAR A/C

Note. Perform REAR A/C SYMPTOM TESTS in order listed.

Rear A/C System Does Not Operate

1. Check rear A/C amplifier. See «REAR A/C AMPLIFIER»(ref-98895-S14713355932001060500000) under SYSTEM TESTS.
2. Check ACC power source circuit. See «ACC POWER SOURCE CIRCUIT»(ref-98895-S02437621282001060500000) under SYSTEM TESTS.

1. Check rear heater main relay. See «RELAYS»(ref-98895-S31781469152001072000000) under COMPONENT TESTS.
2. Check rear blower motor. See «BLOWER MOTOR»(ref-98895-S33075614572001072000000) under COMPONENT TESTS.
3. Check rear blower motor power transistor (heater or cooler). See «REAR BLOWER MOTOR POWER TRANSISTORS»(ref-98895-S38654375432001060500000) under COMPONENT TESTS.
4. Check rear A/C amplifier. See «REAR A/C AMPLIFIER»(ref-98895-S14713355932001060500000) under SYSTEM TESTS.
5. Check solar sensor circuit. See «DTC 21: SOLAR SENSOR CIRCUIT»(ref-98895-S40225436832001060500000) under DIAGNOSTIC TESTS.

1. Check rear blower motor. See «BLOWER MOTOR»(ref-98895-S33075614572001072000000) under COMPONENT TESTS.
2. Check rear blower motor power transistor (heater or cooler). See «REAR BLOWER MOTOR POWER TRANSISTORS»(ref-98895-S38654375432001060500000) under COMPONENT TESTS.

1. Ensure A/C system has proper refrigerant charge. See «A/C SYSTEM PERFORMANCE»(ref-98895-S39981270312001060500000) under SYSTEM TESTS. Correct refrigerant quantity as necessary.
2. Ensure drive belt tension is correct. See «COMPRESSOR BELT TENSION»(ref-98895-S17855320022001060500000) under ADJUSTMENTS. Replace drive belt as necessary.
3. Inspect A/C system performance. See «A/C SYSTEM PERFORMANCE»(ref-98895-S39981270312001060500000) under SYSTEM TESTS.
4. Check compressor magnetic clutch circuit. See «COMPRESSOR MAGNETIC CLUTCH CIRCUIT»(ref-98895-S15568180892001060500000) under SYSTEM TESTS.
5. Check pressure switch circuit. See «DTC 23: REFRIGERANT PRESSURE SENSOR CIRCUIT»(ref-98895-S10317629412001060500000) under DIAGNOSTIC TESTS.
6. Check rear air mix damper position sensor circuit. See «DTC 37 & 47: REAR AIR MIX DAMPER POSITION SENSOR CIRCUIT»(ref-98895-S35583094072001060500000) under DIAGNOSTIC TESTS.
7. Check rear air mix damper control servomotor circuit. See «DTC 47: REAR AIR MIX DAMPER CONTROL SERVOMOTOR»(ref-98895-S25423321132001060500000) under DIAGNOSTIC TESTS.
8. Check rear in-vehicle air temperature sensor circuit. See «DTC 19: REAR IN-VEHICLE AIR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S28917564292001060500000) under DIAGNOSTIC TESTS.
9. Check ambient air temperature sensor circuit. See «DTC 12: AMBIENT AIR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S08305194542001060500000) under DIAGNOSTIC TESTS.
10. Check rear A/C amplifier. See «REAR A/C AMPLIFIER»(ref-98895-S14713355932001060500000) under SYSTEM TESTS.

1. Check rear air mix damper position sensor circuit. See «DTC 37 & 47: REAR AIR MIX DAMPER POSITION SENSOR CIRCUIT»(ref-98895-S35583094072001060500000) under DIAGNOSTIC TESTS.
2. Check rear air mix damper control servomotor circuit. See «DTC 47: REAR AIR MIX DAMPER CONTROL SERVOMOTOR»(ref-98895-S25423321132001060500000) under DIAGNOSTIC TESTS.
3. Check rear in-vehicle air temperature sensor circuit. See «DTC 19: REAR IN-VEHICLE AIR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S28917564292001060500000) under DIAGNOSTIC TESTS.
4. Check ambient air temperature sensor circuit. See «DTC 12: AMBIENT AIR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S08305194542001060500000) under DIAGNOSTIC TESTS.
5. Check rear evaporator temperature sensor circuit. See «DTC 17: REAR EVAPORATOR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S36391294682001060500000) under DIAGNOSTIC TESTS.
6. Check rear A/C amplifier. See «REAR A/C AMPLIFIER»(ref-98895-S14713355932001060500000) under SYSTEM TESTS.

1. Ensure A/C system has proper refrigerant charge. See «A/C SYSTEM PERFORMANCE»(ref-98895-S39981270312001060500000) under SYSTEM TESTS. Correct refrigerant quantity as necessary.
2. Ensure drive belt tension is correct. See «COMPRESSOR BELT TENSION»(ref-98895-S17855320022001060500000) under ADJUSTMENTS. Replace drive belt as necessary.
3. Inspect A/C system performance. See «A/C SYSTEM PERFORMANCE»(ref-98895-S39981270312001060500000) under SYSTEM TESTS.
4. Check electric condenser fan system. See «ELECTRIC CONDENSER FAN»(ref-98895-S31542622222001060500000) under COMPONENT TESTS.
5. Check solar sensor circuit. See «DTC 21: SOLAR SENSOR CIRCUIT»(ref-98895-S40225436832001060500000) under DIAGNOSTIC TESTS.
6. Check rear in-vehicle air temperature sensor circuit. See «DTC 19: REAR IN-VEHICLE AIR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S28917564292001060500000) under DIAGNOSTIC TESTS.
7. Check ambient air temperature sensor circuit. See «DTC 12: AMBIENT AIR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S08305194542001060500000) under DIAGNOSTIC TESTS.
8. Check rear evaporator temperature sensor circuit. See «DTC 17: REAR EVAPORATOR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S36391294682001060500000) under DIAGNOSTIC TESTS.
9. Check rear air mix damper position sensor circuit. See «DTC 37 & 47: REAR AIR MIX DAMPER POSITION SENSOR CIRCUIT»(ref-98895-S35583094072001060500000) under DIAGNOSTIC TESTS.
10. Check rear air mix damper control servomotor circuit. See «DTC 47: REAR AIR MIX DAMPER CONTROL SERVOMOTOR»(ref-98895-S25423321132001060500000) under DIAGNOSTIC TESTS.
11. Check condenser fins for blockage or damage. If fins are bent, straighten using a screwdriver or pliers. Check condenser and fittings for refrigerant leaks. Repair as necessary.
12. Check evaporator and fittings for refrigerant leaks.
13. Check heater core and fittings for coolant leaks.
14. Check expansion valve operation. See «EXPANSION VALVE»(ref-98895-S17853859232001060500000) under COMPONENT TESTS.
15. Check rear A/C amplifier. See «REAR A/C AMPLIFIER»(ref-98895-S14713355932001060500000) under SYSTEM TESTS.

1. Check rear in-vehicle air temperature sensor circuit. See «DTC 19: REAR IN-VEHICLE AIR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S28917564292001060500000) under DIAGNOSTIC TESTS.
2. Check ambient air temperature sensor circuit. See «DTC 12: AMBIENT AIR TEMPERATURE SENSOR CIRCUIT»(ref-98895-S08305194542001060500000) under DIAGNOSTIC TESTS.
3. Check rear air mix damper position sensor circuit. See «DTC 37 & 47: REAR AIR MIX DAMPER POSITION SENSOR CIRCUIT»(ref-98895-S35583094072001060500000) under DIAGNOSTIC TESTS.
4. Check rear air mix damper control servomotor circuit. See «DTC 47: REAR AIR MIX DAMPER CONTROL SERVOMOTOR»(ref-98895-S25423321132001060500000) under DIAGNOSTIC TESTS.
5. Check rear A/C amplifier. See «REAR A/C AMPLIFIER»(ref-98895-S14713355932001060500000) under SYSTEM TESTS.

Indicator Check

1. Turn ignition on while simultaneously depressing AUTO and recirculation/fresh air button on A/C ECU control panel. (Scheme 32)or (Scheme 33). A/C ECU will begin an indicator check.
2. All indicators on A/C ECU control panel should illuminate and turn off 4 times, in one second intervals. To end indicator check, press OFF button. When indicator check is completed, A/C ECU will automatically begin sensor check mode and display any Diagnostic Trouble Code (DTC) detected.
3. On models without navigation system, DTCs are displayed at display panel temperature display. If a slower display rate is desired, press TEMP control button and change DTC display to step operation. Each time TEMP control button is pressed, display will change one step.
4. On models with navigation system, DTCs are displayed at navigation display panel temperature display. If a slower display rate is desired, press defrost button. Each time defrost button is pressed, display will change one step.
5. On all models, record displayed DTCs and proceed to appropriate DTC diagnostic procedure. See «DIAGNOSTIC TROUBLE CODES»(ref-98895-S23260113972001060500000) table. To exit self-diagnostics, depress OFF button. DTCs will not be cleared.
6. To activate actuator check, see «ACTUATOR CHECK»(ref-98895-S42162457782001060500000). To clear DTCs, see «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-98895-S07494897382001060500000).

DIAGNOSTIC TROUBLE CODES

Actuator Check

Note. Actuators are also referred to as servomotors.

1. Perform procedure for retrieving DTCs. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-98895-S33761220592001060500000). After beginning sensor check mode, depress recirculation/fresh air button. (Scheme 32)or (Scheme 33).
2. Actuator check will begin. Each damper, motor and relay will operate at one second intervals beginning in order from 20. Component operation numbers are displayed in temperature display. Use actuator check table to identify corresponding operating modes. (Scheme 36)or (Scheme 37). Confirm correct temperature and airflow operation visually and by hand.
3. Record displayed codes. When displayed codes change, a buzzer will sound. On models without navigation, to slow display rate and change to step operation, press A/C button. On models with navigation, to slow display rate and change to step operation, press defrost button.
4. For DTC description and diagnosis, see «DIAGNOSTIC TROUBLE CODES»(ref-98895-S23260113972001060500000) table. For air outlet servomotor diagnosis, see «AIR OUTLET (VENT MODE) SERVOMOTOR»(ref-98895-S24155773152001060500000) under COMPONENT TESTS. On all models, to cancel actuator check mode, press OFF button.

Scheme 36

Scheme 37

SYSTEM TESTS

A/C SYSTEM PERFORMANCE

1. Park vehicle out of direct sunlight. Install A/C manifold gauge set. Set A/C controls to recirculated air position with inlet air temperature at 86-95°F (30-35°C). Start engine and allow to operate at 2000 RPM.
2. Set blower motor switch to high speed and temperature control switch to maximum cooling. High-side pressure should be about 199-228 psi (14-16 kg/cm 2 ). Low-side pressures should be about 21-36 psi (1.5-2.5 kg/cm 2 ). Pressures will vary slightly based on ambient temperatures.

A/C ECU (W/O Navigation System)

Remove A/C ECU, with connectors still connected. See A/C ECU (FRONT AMPLIFIER) under REMOVAL & INSTALLATION. Backprobe and check for continuity between A/C ECU connector terminal C11-22 (White/Black wire) and body ground. (Scheme 38) If continuity does not exist, repair ground circuit as necessary. See WIRING DIAGRAMS. If continuity exists, replace A/C ECU with a known-good ECU and retest system.

A/C ECU (W/ Navigation System)

Remove A/C ECU, with connectors still connected. See A/C ECU (FRONT AMPLIFIER) under REMOVAL & INSTALLATION. Backprobe and check for continuity between A/C ECU connector terminal C26-11 (White/Black wire) and body ground. (Scheme 39)and (Scheme 40). If continuity does not exist, repair ground circuit as necessary. See WIRING DIAGRAMS. If continuity exists, replace A/C ECU with a known-good ECU and retest system.

Rear A/C Amplifier

Remove rear A/C amplifier, leaving wiring harness connectors attached. See A/C ECU (FRONT AMPLIFIER) under REMOVAL & INSTALLATION. Backprobe and check for continuity between A/C amplifier connector terminal A33-22 (White/Black wire) and body ground. (Scheme 41) If continuity does not exist, repair ground circuit as necessary. See WIRING DIAGRAMS. If continuity exists, replace A/C amplifier with a known-good amplifier and retest system.

ACC POWER SOURCE 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 C11-2 (Gray wire) and C11-22 (White/Black wire). (Scheme 38)
3. With navigation system, backprobe and measure voltage between A/C ECU connector terminals C26-13 (Gray wire) and C26-11 (White/Black wire). (Scheme 39)and (Scheme 40).
4. If voltage is 10-14 volts, temporarily substitute a known-good A/C ECU and retest system. If 10-14 volts does not exist, go to next step.
5. Without navigation system, check for continuity between ground and A/C ECU connector terminal C11-22 (White/Black wire). With navigation system, check for continuity between ground and A/C ECU connector terminal C26-11 (White/Black wire). If continuity exists, go to next step. If continuity does not exist, repair or replace wiring harness or connector as necessary.
6. Remove CIGAR fuse (15-amp) from left side cowl junction block, located behind driver side kick panel. If fuse is okay, repair or replace wiring harness or connector between left side cowl junction block and A/C ECU. If fuse is not okay, check for short in CIGAR fuse circuit. Repair or replace as necessary. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).

2000 Models

1. Remove A/C ECU, with connectors still connected. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION.
2. Backprobe and measure voltage between ground and A/C ECU connector terminal C11-12 (Blue/White wire). (Scheme 38) See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. If battery voltage exists, no problem is present at this time. If battery voltage does not exist, check ECU-B fuse (15-amp) located in left kick panel junction block. Replace fuse as necessary.
4. If fuse is okay, repair or replace wiring harness or connector between junction block and rear A/C amplifier. If fuse is not okay, check for short in ECU-B fuse circuit, repair as necessary. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).

2001 Models

1. Remove A/C ECU, with connectors still connected. See «A/C ECU (FRONT AMPLIFIER)»(ref-98895-S33179739282001060500000) under REMOVAL & INSTALLATION.
2. Without navigation system, backprobe and measure voltage between ground and A/C ECU connector terminal C11-12 (Green/Red wire). (Scheme 38) See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. With navigation system, backprobe and measure voltage between ground and A/C ECU connector terminal C24-11 (Green/Red wire). (Scheme 39)and (Scheme 40). See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
4. On all models, if battery voltage exists, no problem is present at this time. If battery voltage does not exist, check ECU-B1 fuse (20-amp), located in left engine compartment junction block. Replace fuse as necessary.
5. If fuse is okay, repair or replace wiring harness or connector between junction block and A/C ECU. If fuse is not okay, check for short in ECU-B1 fuse circuit and repair as necessary. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).

COMPRESSOR MAGNETIC CLUTCH CIRCUIT

1. Remove A/C ECU, with connectors still connected. Start engine and allow to idle. Turn AUTO button on and off.
2. Without navigation system, backprobe and measure voltage between ground and A/C ECU connector terminal C9-14 (Blue wire). (Scheme 38) See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. With navigation system, backprobe and measure voltage between ground and A/C ECU connector terminal C28-11 (Blue wire). (Scheme 39)and (Scheme 40). See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
4. With AUTO switch off, voltage is 10-14 volts. With AUTO switch on, voltage is zero volts. If voltage is as specified, check ECM and/or A/C ECU. Replace as necessary. If voltage is not as specified, go to next step.
5. Disconnect A/C magnetic clutch connector located on top of compressor. Using a fused jumper wire, connect battery voltage to A/C magnetic clutch connector terminal No. 3 (Black/Yellow wire). see scheme 8 If compressor clutch energizes, go to next step. If compressor clutch does not energize, replace A/C magnetic clutch.
6. Check wiring harness and connections between A/C ECU and A/C magnetic clutch relay. Repair as necessary. If wiring harness and connections are okay, replace A/C ECU and retest A/C system.

FRONT A/C ECU (W/O NAVIGATION SYSTEM)

Remove A/C ECU, with connectors still connected. See A/C ECU (FRONT AMPLIFIER) under REMOVAL & INSTALLATION. Turn ignition on unless instructed otherwise. Backprobe and measure voltage or check for continuity between indicated connector terminals. (Scheme 38) If circuits do not test as specified, inspect circuit and related components. See WIRING DIAGRAMS. If circuits test as specified, temporarily install a known-good A/C ECU and recheck operation of A/C system.

Scheme 38

C11-1 & C11-22

With ignition turned from OFF to ON position, 10-14 volts should be present.

C11-2 & C11-22

With ignition turned to ACC position, voltage is 10-14 volts.

C11-6 & C11-22

Turn ignition on. With fresh air mode switch pressed, voltage should be less than one volt. With recirculation mode switch pressed, voltage is 10-14 volts.

C11-7 & C11-22

Turn ignition on. With fresh air mode switch pressed, voltage is 10-14 volts. With recirculation mode switch pressed, voltage should be less than one volt.

C11-8 & C11-22

Turn ignition on. With temperature set to maximum cool, voltage is 10-14 volts. With temperature set to maximum hot, voltage should be less than one volt.

C11-9 & C11-22

Turn ignition on. With temperature set to maximum cool, voltage should be less than one volt. With temperature set to maximum hot, voltage is 10-14 volts.

C11-12 & C11-22

Voltage should be 10-14 volts with ignition on or off.

C10-1 & C10-12

With ignition on, 4.4-5.5 volts should be present.

C10-2 & C10-12

Turn ignition on. With in-vehicle air temperature at 77°F (25°C), 1.8-2.2 volts should be present. With in-vehicle air temperature at 104°F (40°C), 1.2-1.6 volts should be present.

C10-3 & C10-12

Turn ignition on. With ambient air temperature at 77°F (25°C), 1.3-1.8 volts should be present. With ambient air temperature at 104°F (40°C), 0.8-1.3 volts should be present.

C10-4 & C10-12

With front evaporator temperature at 32°F (0°C), 2.0-2.4 volts should be present. With front evaporator temperature at 59°F (15°C), 1.4-1.8 volts should be present.

C10-6 & C10-12

Turn ignition on. With solar sensor exposed to artificial light, 0.8-4.3 volts should be present. With solar sensor covered, less than 0.8 volts should be present.

C10-8 & C10-12

Turn ignition on. With temperature set to maximum cool, 3.5-4.5 volts should be present. With temperature set to maximum hot, 0.5-1.5 volts should be present.

C10-9 & C10-12

Turn ignition on. With recirculation mode switch pressed, 3.5-4.5 volts should be present. With fresh air mode switch pressed, 0.5-1.5 volts should be present.

C9-3 & C11-22

Select any operating mode, except face (panel) mode. When face mode is selected, voltage should change from 10-14 volts to less than one volt.

C9-4 & C11-22

Select any operating mode, except bi-level mode. When bi-level mode is selected, voltage should change from 10-14 volts to less than one volt.

C9-5 & C11-22

Select any operating mode, except floor (foot) mode. When floor mode is selected, voltage should change from 10-14 volts to less than one volt.

C9-10 & C11-22

Select any operating mode, except floor/defrost mode. When floor/defrost mode is selected, voltage should change from 10-14 volts to less than one volt.

C9-11 & C11-22

Select any operating mode, except defrost mode. When defrost mode is selected, voltage should change from 10-14 volts to less than one volt.

C9-12 & C11-22

When blower motor is turned from off to on, voltage should change from 10-14 volts to less than one volt.

C9-13 & C11-22

When blower motor is turned from off to on, voltage should change from 10-14 volts to less than one volt.

C9-14 & C11-22

When A/C compressor is turn from off to on, voltage should change from 10-14 volts to less than one volt.

C8-7 & C10-12

Start engine. With A/C compressor on, voltage should pulse.

C8-9 & C11-22

On 2000 models, turn ignition on. With engine coolant temperature at 77°F (25°C), voltage should be 1.8-2.2 volts. With coolant temperature at 104°F (40°C), voltage should be 1.2-1.6 volts. On 2001 models, with ignition on, voltage should pulse.

C8-10 & C11-22

With A/C refrigerant pressure less than 28 psi (2.0 kg/cm 2 ) or more than 455 psi (32 kg/cm 2 ), voltage should range from 10-14 volts to less than one volt.

C8-13 & C11-22

With engine operating at idle, voltage should pulse.

C8-22 & C11-22

Turn ignition off. Raise and support vehicle. Turn ignition on, engine off. Manually rotate drive shaft. Voltage should pulse.

C8-23 & C11-22

Start engine and allow to idle. Press A/C switch to ON position. With compressor magnetic clutch engaged, voltage is 10-14 volts. With compressor magnetic clutch not engaged, voltage is less than one volt.

FRONT A/C ECU (W/ NAVIGATION SYSTEM)

Remove A/C ECU, with connectors still connected. See A/C ECU (FRONT AMPLIFIER) under REMOVAL & INSTALLATION. Turn ignition on unless instructed otherwise. Backprobe and measure voltage or check for continuity between indicated connector terminals. (Scheme 39)and (Scheme 40).

When measuring voltages between specified terminals, check for voltage changes during component activation. If circuits do not test as specified, inspect circuit and related components. See WIRING DIAGRAMS . If circuits test as specified, temporarily install a known-good A/C ECU and recheck operation of A/C system.

Scheme 39

Scheme 40

C26-1 & C26-11

Voltage is always 10-14 volts.

C26-2 & C26-11

Turn ignition on. With parking lights on, voltage should be 10-14 volts.

C26-4 & C26-11

When A/C refrigerant pressure changes to less than 28 psi (2.0 kg/cm 2 ) or more than 455 psi (32 kg/cm 2 ), voltage should range from 10-14 volts to less than one volt.

C26-6 & C26-11

Turn ignition on. Rotate front wheel slowly. Voltage should pulse.

C26-7 & C26-11

With ignition on, voltage should pulse.

C26-8 & C26-11

Start engine and allow to idle. Press A/C switch to ON position. With compressor magnetic clutch engaged, voltage is 10-14 volts. With compressor magnetic clutch not engaged, voltage is less than one volt.

C26-11 & Ground

Continuity should be constant.

C26-12 & C26-11

With ignition on, voltage should be 10-14 volts.

C26-13 & C26-11

With ignition in ACC position, voltage should be 10-14 volts.

C26-15 & C26-11

Turn ignition on. With front A/C and rear A/C turned on, voltage should be less than one volt. With rear A/C off, voltage should be 10-14 volts.

C26-16 & C26-11

Turn ignition on. With fresh air mode switch pressed, voltage should be less than one volt. With recirculation mode switch pressed, voltage is 10-14 volts.

C26-17 & C26-11

Turn ignition on. With fresh air mode switch pressed, voltage is 10-14 volts. With recirculation mode switch pressed, voltage should be less than one volt.

C26-18 & C26-11

Turn ignition on. With front air temperature control set to maximum cool, voltage should be less than one volt. With front air temperature control set to maximum warm, voltage should be 10-14 volts.

C26-19 & C26-11

Turn ignition on. With front air temperature control set to maximum warm, voltage should be less than one volt. With front air temperature control set to maximum cool, voltage should be 10-14 volts.

C26-21 & C26-11

Continuity should be constant.

C26-22 & C26-11

With dual A/C, voltage should be less than one volt.

C25-2 & C25-1

Turn ignition on. With solar sensor exposed to artificial light, 0.8-4.3 volts should be present. With solar sensor covered, less than 0.8 volts should be present.

C25-3 & C25-1

Turn ignition on. With ambient air temperature at 77°F (25°C), voltage should be 1.8-2.2 volts. With ambient air temperature at 104°F (40°C), voltage should be 1.2-1.6 volts.

C25-5 & C25-1

Turn ignition on. With front air temperature control set to maximum warm, voltage should be less than one volt. With front air temperature control set to maximum cool, voltage should be 3.5-4.5 volts.

C25-7 & C26-11

Communication circuit between front A/C amplifier and rear A/C amplifier.

C25-8 & C26-11

Communication circuit between front A/C amplifier and rear A/C amplifier.

C25-9 & C26-1

With ignition turned on, voltage should be 4.5-5.5 volts.

C25-10 & C25-1

Turn ignition on. With front in-vehicle temperature at 77°F (25°C), 1.8-2.2 volts should be present. With front in-vehicle temperature at 104°F (40°C), 1.2-1.6 volts should be present.

C25-11 & C25-1

Turn ignition on. With front A/C evaporator temperature at 32°F (0°C), 2.0-2.4 volts should be present. With front A/C evaporator temperature at 59°F (15°C), 1.4-1.8 volts should be present.

C25-13 & C25-1

Turn ignition on. With fresh air mode switch pressed, less than one volt should be present. With recirculation mode switch pressed, 3.5-4.5 volts should be present.

C25-15 & C26-11

Communication circuit between front A/C amplifier and rear A/C amplifier.

C25-16

Communication circuit between front A/C amplifier and rear A/C amplifier.

C27-1

Multiplex communication circuit.

C27-2 & C26-11

Communication circuit between front A/C amplifier and clock.

C27-3

Communication circuit between front A/C amplifier and center cluster integration panel.

C27-6 & C26-11

Turn ignition on. With defrost mode selected, voltage should be less than one volt. Without defrost mode selected, voltage is 10-14 volts.

C27-8 & C26-11

Turn ignition on. With bi-level mode selected, voltage should be less than one volt. Without bi-level mode selected, voltage is 10-14 volts.

C27-9 & C26-11

With ignition on, voltage should pulse.

C27-10

Multiplex communication circuit.

C27-11

Communication circuit between front A/C amplifier and center cluster integration panel.

C27-12

Communication circuit between front A/C amplifier and center cluster integration panel.

C27-13

Communication circuit between front A/C amplifier and center cluster integration panel.

C27-15 & C26-11

With engine operating at idle and A/C compressor magnetic clutch engaged, voltage should pulse.

C27-16 & C26-11

Turn ignition on. With foot/defrost mode selected, voltage should be less than one volt. Without foot/defrost mode selected, voltage is 10-14 volts.

C27-17 & C26-11

Turn ignition on. With foot mode selected, voltage should be less than one volt. Without foot mode selected, voltage is 10-14 volts.

C27-18 & C26-11

Turn ignition on. With face/vent mode selected, voltage should be less than one volt. Without face/vent mode selected, voltage is 10-14 volts.

C28-3 & C26-11

Turn ignition on. With rear defogger switch on, voltage should be less than one volt. With rear defogger switch off, voltage is 10-14 volts.

C28-4 & C26-11

Start engine and allow to idle. Press A/C switch to ON position. With compressor magnetic clutch engaged, voltage is less than one volt. With compressor magnetic clutch not engaged, voltage is 10-14 volts.

C28-7 & C26-11

If equipped with rear heater, turn ignition on. With front, rear heater switch on, voltage is less than one volt. With front, rear heater switch off, voltage is 10-14 volts.

C28-11 & C26-11

Start engine and allow to idle. Press A/C switch to ON position. With compressor magnetic clutch engaged, voltage is less than one volt. With compressor magnetic clutch not engaged, voltage is 10-14 volts.

C28-12 & C26-11

Turn ignition on. With blower motor operating, voltage is less than one volt. With blower motor not operating, voltage is 10-14 volts.

C28-13 & C26-11

Turn ignition on. With blower motor operating, voltage is less than one volt. With blower motor not operating, voltage is 10-14 volts.

Remove rear A/C amplifier, with connectors still connected. See REAR HEATER UNIT under REMOVAL & INSTALLATION. Turn ignition on unless instructed otherwise. Backprobe and measure voltage or check for continuity between indicated connector terminals. (Scheme 41)

When measuring voltages between specified terminals, check for voltage changes during component activation. If circuits do not test as specified, inspect circuit and related components. See WIRING DIAGRAMS . If circuits test as specified, temporarily install a known-good rear A/C amplifier and recheck operation of rear A/C system.

Scheme 41

A33-1 & A33-22

Voltage is 10-14 volts at all times.

A33-2 & A33-22

With ignition on, voltage is 10-14 volts. With ignition off, no voltage should exist.

A33-3 & A33-22

Set rear A/C to face mode. With rear blower motor switch set to low (LO) speed, voltage is 7.4 volts. With rear blower motor switch set to medium speed, voltage is 4.2 volts. With rear blower motor switch set to high (HI) speed, voltage is 0.5 volt.

A33-4 & A33-22

Set rear A/C to face mode. With rear blower motor OFF button pressed, voltage is less than one volt. With rear blower motor switch set to low (LO) speed, voltage is 1.5-3.0 volts.

A33-5 & A33-9

With ignition on, voltage is 4.5-5.5 volts.

A33-6 & A33-9

When rear A/C temperature control switch is moved from maximum cool to maximum hot, voltage will change from 4.0 volts to one volt.

A33-7 & A33-9

When rear evaporator temperature is 32°F (0°C), voltage is 2.0-2.4 volts. When rear evaporator temperature is 59°F (15°C), voltage is 1.4-1.8 volts.

A33-8 & A33-9

When rear air inlet temperature is 77°F (25°C), voltage is 1.5-1.9 volts. When rear air inlet temperature is 104°F (40°C), voltage is 1.2-1.6 volts.

A33-9 & A33-22

Continuity should be constant.

A33-11 & A33-22

When rear A/C temperature control switch is moved from maximum hot position to maximum cool position, voltage will change from less than one volt to 10-14 volts for 16 seconds.

A33-12 & A33-22

When rear A/C temperature control switch is moved from maximum cool position to maximum hot position, voltage will change from less than one volt to 10-14 volts for 16 seconds.

A33-13 & A33-22

Set rear A/C to face mode. When rear blower motor operation is changed from off to low (LO) speed, voltage will change from 10-14 volts to less than one volt.

A33-14 & A33-22

Set rear A/C to foot mode. When rear blower motor operation is changed from off to low (LO) speed, voltage will change from 10-14 volts to less than one volt.

A33-15 & A33-22

Set rear A/C to foot mode. With rear blower motor switch set to low (LO) speed, voltage is 7.4 volts. With rear blower motor switch set to medium speed, voltage is 4.2 volts. With rear blower motor switch set to high (HI) speed, voltage is 0.5 volt.

A33-16 & A33-22

Set rear A/C to foot mode. When rear blower motor operation is changed from off to low (LO) speed, voltage will change from less than one volt to 1.5-3.0 volts.

A33-18 & A33-22

With ignition on, voltage should pulse.

A33-19 & A33-22

With ignition on, voltage should pulse.

A33-20 & A33-22

With ignition on, voltage should pulse.

A33-21 & A33-22

With ignition on, voltage should pulse.

A33-22 & Ground

Continuity should be constant.

A34-1 & A34-8

When rear A/C control panel AUTO button is pushed from off position to on position, voltage will change from 10-14 volts to less than one volt during pushing action.

A34-2 & A34-8

When rear A/C control panel OFF button is pushed from off position to on position, voltage will change from 10-14 volts to less than one volt during pushing action.

A34-3 & A34-8

When rear A/C control panel blower motor low (LO) speed button is pushed from off position to on position, voltage will change from 10-14 volts to less than one volt during pushing action.

A34-4 & A34-8

When rear A/C control panel blower motor medium speed button is pushed from off position to on position, voltage will change from 10-14 volts to less than one volt during pushing action.

A34-5 & A33-22

When any rear A/C control panel button, except AUTO is pressed, voltage will change from 10-14 volts to less than one volt.

A34-6 & A33-22

When any rear A/C control panel button, except blower motor low (LO) speed is pressed, voltage will change from 10-14 volts to less than one volt.

A34-7 & A33-22

When any rear A/C control panel button, except blower motor medium speed is pressed, voltage will change from 10-14 volts to less than one volt.

A34-8 & A33-22

Continuity should be constant.

A34-9 & A33-22

When rear A/C control panel blower motor high (HI) speed button is pushed from off position to on position, voltage will change from 10-14 volts to less than one volt during pushing action.

A34-10 & A33-22

When rear A/C control panel face button is pushed from off position to on position, voltage will change from 10-14 volts to less than one volt during pushing action.

A34-11 & A33-22

When rear A/C control panel bi-level button is pushed from off position to on position, voltage will change from 10-14 volts to less than one volt during pushing action.

A34-12 & A33-22

When rear A/C control panel foot button is pushed from off position to on position, voltage will change from 10-14 volts to less than one volt during pushing action.

A34-15 & A33-22

When any rear A/C control panel button, except face is pressed, voltage will change from 10-14 volts to less than one volt.

A34-16 & A33-22

When any rear A/C control panel button, except bi-level is pressed, voltage will change from 10-14 volts to less than one volt.

A34-17 & A33-22

When any rear A/C control panel button, except foot is pressed, voltage will change from 10-14 volts to less than one volt.

A34-18 & A33-22

When any rear A/C control panel button, except blower motor high (HI) speed is pressed, voltage will change from 10-14 volts to less than one volt.

A35-7 & A35-12

Turn ignition on. With in-vehicle temperature at 77°F (25°C), voltage is 1.8-2.2 volts. With in-vehicle temperature at 104°F (40°C), voltage is 1.2-1.6 volts.

A35-8 & A35-12

When rear A/C temperature control switch is moved from maximum cool position to maximum hot position, voltage will change from 5.0 volts to zero volts.

A35-12 & A33-9

Continuity should be constant.

FRONT BLOWER MOTOR 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 and operate blower motor.
2. Without navigation system, backprobe and measure voltage between ground and A/C ECU connector terminal C9-12 (White/Red wire). (Scheme 38) See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
3. With navigation system, backprobe and measure voltage between ground and A/C ECU connector terminal C28-13 (White/Red wire). (Scheme 39)and (Scheme 40). See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
4. If voltage is 1-3 volts, temporarily substitute a known-good A/C ECU and retest system. If voltage is not as specified, remove blower motor. See «FRONT BLOWER MOTOR UNIT»(ref-98895-S27041991942001060500000) under REMOVAL & INSTALLATION.
5. Check front blower motor operation. See «BLOWER MOTOR»(ref-98895-S33075614572001072000000) under COMPONENTS TESTS. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000). If blower motor operates smoothly, go to next step. Replace blower motor if it does not operate smoothly.
6. Check front blower motor control relay. See «RELAYS»(ref-98895-S31781469152001072000000) under COMPONENT TESTS. If front blower motor control relay is okay, repair or replace wiring harness or connector. If front blower motor control relay is not okay, replace relay.

AIR INLET DAMPER CONTROL SERVOMOTOR

1. Remove air inlet servomotor. Using a fused jumper wire, connect battery voltage to air inlet servomotor terminal No. 7. Connect battery ground to servomotor terminal No. 6. see scheme 9 Servomotor lever should move smoothly to REC (recirculated air) position.
2. Transpose power and ground leads. Servomotor lever should move smoothly to FRS (fresh air) position. see scheme 9 If servomotor does not function as specified, replace servomotor.

AIR INLET DAMPER POSITION SENSOR

1. Remove air inlet servo motor, located on passenger side of blower unit. See «FRONT BLOWER MOTOR UNIT»(ref-98895-S27041991942001060500000) under REMOVAL & INSTALLATION. Disconnect air inlet damper position sensor connector.
2. Measure resistance between front air inlet damper position sensor terminals No. 1 and 5. see scheme 9 Resistance should be 4200-7800 ohms. Replace servomotor if resistance is not as specified.
3. Operate servomotor. See «AIR INLET DAMPER CONTROL SERVOMOTOR»(ref-98895-S01557862162001072300000). Measure resistance between air mix damper control servomotor terminals No. 1 and 5. See «AIR INLET DAMPER CONTROL SERVOMOTOR RESISTANCE»(ref-98895-S26374342382001072300000) table. Replace servomotor if resistance is not as specified.

AIR INLET DAMPER CONTROL SERVOMOTOR RESISTANCE

AIR OUTLET (VENT MODE) SERVOMOTOR

1. Remove air outlet servomotor. See «AIR OUTLET SERVOMOTOR»(ref-98895-S24916462532001072400000) under REMOVAL & INSTALLATION. Using a fused jumper wire, connect battery voltage to air outlet servomotor terminal No. 6. Connect battery ground to air outlet servomotor connector terminal No. 7. (Scheme 42)
2. Using another jumper wire, connect each remaining terminal to battery ground. Servomotor shaft should rotate to specified positions. See «AIR OUTLET SERVOMOTOR OPERATION SPECIFICATIONS»(ref-98895-S30473680112001060500000) table. If operation is not as specified, replace air outlet servomotor.
3. If air outlet servomotor is okay, check wiring harness between servomotor and A/C ECU. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000). Repair as necessary.

AIR OUTLET SERVOMOTOR OPERATION SPECIFICATIONS

Scheme 42

AMBIENT AIR TEMPERATURE SENSOR

Note. When installing ambient temperature sensor, connect sensor connector before reconnecting battery.

Disconnect negative battery cable. Remove clip and ambient temperature sensor from front bumper reinforcement. Disconnect ambient temperature sensor connector. Measure sensor resistance while heating sensor. See AMBIENT TEMPERATURE SENSOR SPECIFICATIONS table. If resistance is not as specified, replace ambient sensor.

AMBIENT TEMPERATURE SENSOR SPECIFICATIONS

ELECTRIC CONDENSER FAN

1. Connect A/C manifold gauge set. Start engine and allow to idle. Set blower motor to high speed. Set temperature control to maximum cool. Turn A/C on. Monitor A/C manifold gauges.
2. Condenser fan should not operate when refrigerant pressure is less than 220 psi (15.5 kg/cm 2 ). Condenser fan should operate when refrigerant pressure is 220 psi (15.5 kg/cm 2 ) or more. If condenser fan does not operate as specified, go to next step.
3. Disconnect condenser fan connector. Using a fused jumper wire, connect battery voltage and an ammeter in-series to terminal No. 2 (Blue/Red wire). Connect connector terminal No. 1 (White/Black wire) to ground. Condenser fan should operate smoothly and amperage should be 6.0-7.4 amps at 68°F (20°C).
4. If condenser fan operation is as specified, check refrigerant pressure switch and condenser fan relay. See «REFRIGERANT PRESSURE SWITCH»(ref-98895-S22557922102001072100000) or «RELAYS»(ref-98895-S31781469152001072000000) . If current is not as specified, replace condenser fan motor.

ENGINE COOLANT TEMPERATURE SENSOR

Remove Engine Coolant Temperature (ECT) sensor, located under throttle body. Immerse ECT and a thermometer in ice water. Slowly heat water while measuring ECT sensor resistance. ECT sensor resistance should decrease as temperature increases. Replace ECT sensor if resistance is not as specified. (Scheme 43)and (Scheme 44).

Scheme 43

Scheme 44

EXHAUST GAS SENSOR

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

1. Remove and disconnect exhaust gas sensor, located on radiator core support center bracket, next to condenser fan. Using a fused jumper wire apply battery voltage to sensor terminal No. 4 and battery ground to sensor terminal No. 1. (Scheme 45)
2. Wait at least 30 seconds and measure resistance between exhaust gas sensor terminals No. 2 and 3. Resistance should be 5000-100,000 ohms at 50-95°F (10-35°C). Replace exhaust sensor if resistance is not as specified.

Scheme 45

Front & Rear

Ensure A/C system refrigerant is fully charged. See A/C SYSTEM PERFORMANCE under SYSTEM TESTS. Install A/C manifold gauge set. Start and operate engine for 5 minutes. Ensure high pressure reading is about 199-228 psi (14-16 kg/cm 2 ). If low pressure reading drops to 0 psi (0 kg/cm 2 ), replace expansion valve. See EXPANSION VALVE under REMOVAL & INSTALLATION.

FRONT AIR MIX DAMPER CONTROL SERVOMOTOR

1. Remove air mix damper control servomotor, is located on underside of front heater unit. See «FRONT HEATER UNIT»(ref-98895-S25169341812001060500000) under REMOVAL & INSTALLATION. Disconnect front air mix damper servomotor connector.
2. Using a fused jumper wire, apply battery voltage to air mix damper control servomotor terminal No. 3. Connect battery ground to terminal No. 2. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000). Servomotor lever should move smoothly to HOT position. (Scheme 46)
3. Transpose power and ground leads. Servomotor lever should move smoothly to COOL position. (Scheme 46) If servomotor does not function as specified, replace servomotor.

Scheme 46

FRONT AIR MIX DAMPER CONTROL SERVOMOTOR POSITION SENSOR

1. Remove air mix damper control servomotor, located on underside of front heater unit. See «FRONT HEATER UNIT»(ref-98895-S25169341812001060500000) under REMOVAL & INSTALLATION. Disconnect front air mix damper servomotor connector.
2. Measure resistance between front air mix damper servomotor terminals No. 4 and 6. (Scheme 46) If resistance 4200-7800 ohms, go to next step. If resistance is not 4200-7800 ohms, replace front air mix damper servomotor.
3. Operate air mix damper control servomotor. See «FRONT AIR MIX DAMPER CONTROL SERVOMOTOR»(ref-98895-S30278464872001072100000). Measure resistance between front air mix damper servomotor terminals No. 4 and 6 in each lever position. (Scheme 46) See «AIR MIX DAMPER CONTROL SERVOMOTOR POSITION SENSOR RESISTANCE»(ref-98895-S07467959022001072100000) table. Replace servomotor if resistance is not as specified.

AIR MIX DAMPER CONTROL SERVOMOTOR POSITION SENSOR RESISTANCE

Front Blower Motor

Using a fused jumper wire, connect battery voltage to blower motor terminal No. 4 (M+). Connect battery ground to blower motor terminal No. 5 (M-). (Scheme 51) See WIRING DIAGRAMS. Replace blower motor if it does not operate smoothly.

Rear Heater & Rear Cooler Blower Motors

Using a fused jumper wire, connect battery voltage to blower motor terminal No. 1 (Blue wire). Connect battery ground to blower motor terminal No. 2 (Blue/Black wire on heater motor; White wire on cooler motor). See WIRING DIAGRAMS . Replace blower motor if it does not operate smoothly.

FRONT EVAPORATOR TEMPERATURE SENSOR

1. Remove instrument panel. See «INSTRUMENT PANEL»(ref-98895-S15316322352001060500000) under REMOVAL & INSTALLATION. Remove air duct from evaporator unit. Remove aspirator hose bolt. Disconnect sensor and carefully pry out evaporator sensor. Carefully detach sensor from bracket plate.
2. Immerse evaporator sensor at least 4" (100 mm) into ice water with a thermometer. Measure evaporator temperature sensor resistance at specified temperatures. See «EVAPORATOR TEMPERATURE SENSOR SPECIFICATIONS»(ref-98895-S24927971792001072300000) table. Replace evaporator temperature sensor if sensor resistance is not as specified.

EVAPORATOR TEMPERATURE SENSOR SPECIFICATIONS

IN-VEHICLE AIR TEMPERATURE SENSOR

Note. Testing for front and rear in-vehicle (room) air temperature sensors is similar.

Disconnect front in-vehicle air temperature sensor, located in lower No. 1 steering column panel. Disconnect rear in-vehicle air temperature sensor, located in rear heater unit. Measure suspect sensor resistance between sensor terminals while heating sensor. See IN-VEHICLE TEMPERATURE SENSOR SPECIFICATIONS table. If resistance is not as specified, replace in-vehicle temperature sensor.

IN-VEHICLE TEMPERATURE SENSOR SPECIFICATIONS

Using a small, flat-blade screwdriver with tip taped, release 4 claws and remove rear A/C control panel. Disconnect electrical connector.

REAR AIR MIX DAMPER CONTROL SERVOMOTOR

1. Remove rear air mix damper control servomotor, located on rear heater unit. See «REAR HEATER UNIT»(ref-98895-S35025136772001060500000) under REMOVAL & INSTALLATION. Disconnect rear air mix damper control servomotor connector.
2. Using a fused jumper wire, apply battery voltage to rear air mix damper control servomotor terminal No. 1. Connect battery ground to terminal No. 2. See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000). Servomotor lever should move smoothly to HOT position. (Scheme 47)
3. Transpose power and ground leads. Servomotor lever should move smoothly to COOL position. (Scheme 47) If servomotor does not function as specified, replace servomotor.

Scheme 47

REAR AIR MIX DAMPER CONTROL SERVOMOTOR POSITION SENSOR

1. Remove rear air mix damper control servomotor, located on rear heater unit. See «REAR HEATER UNIT»(ref-98895-S35025136772001060500000) under REMOVAL & INSTALLATION. Disconnect rear air mix damper control servomotor connector.
2. Measure resistance between rear air mix damper servomotor position sensor terminals No. 3 and 4. (Scheme 47) Resistance should be 4200-7800 ohms. If resistance is as specified, go to next step. If resistance is not as specified, replace rear air mix damper control servomotor.
3. Operate air mix damper control servomotor. See «REAR AIR MIX DAMPER CONTROL SERVOMOTOR»(ref-98895-S25419838552001072600000). Measure resistance between rear air mix damper servomotor terminals No. 3 and 4 in each lever position. (Scheme 47) See «REAR AIR MIX DAMPER CONTROL SERVOMOTOR POSITION SENSOR RESISTANCE»(ref-98895-S00670143932001072600000) table. Replace servomotor if resistance is not as specified.

REAR AIR MIX DAMPER CONTROL SERVOMOTOR POSITION SENSOR RESISTANCE

REAR EVAPORATOR MAGNETIC VALVE

Note. Rear evaporator magnetic valve and expansion valve are incorporated as a unit.

Remove magnetic valve from rear evaporator. See REAR COOLING UNIT under REMOVAL & INSTALLATION. Check air passage through valve with 10-14 volts and ground applied to magnetic valve terminals. With voltage applied, air should flow through valve. Without voltage applied, air passage should be closed. If valve operates as specified, check wiring and connectors. If valve does not operate as specified, replace magnetic valve and expansion valve.

REAR EVAPORATOR TEMPERATURE SENSOR

1. Remove and disconnect rear evaporator temperature sensor. Rear sensor is located on evaporator, in rear cooling unit. See «REAR COOLING UNIT»(ref-98895-S31098752402001060500000) under REMOVAL & INSTALLATION. Immerse evaporator sensor
2. Immerse evaporator sensor at least 4" (100 mm) into ice water with a thermometer. Measure evaporator temperature sensor resistance at specified temperatures. See «REAR EVAPORATOR TEMPERATURE SENSOR RESISTANCE»(ref-98895-S15844561512001072700000) table. Replace evaporator temperature sensor if sensor resistance is not as specified.

REAR EVAPORATOR TEMPERATURE SENSOR RESISTANCE

REAR INLET AIR TEMPERATURE SENSOR

Remove rear inlet air temperature sensor. See REAR INLET AIR TEMPERATURE SENSOR under REMOVAL & INSTALLATION. Disconnect sensor connector. Measure resistance between sensor terminals at specified temperatures. If resistance is not as specified, replace sensor.

REAR INLET AIR TEMPERATURE SENSOR RESISTANCE

REAR IN-VEHICLE TEMPERATURE SENSOR

Disconnect rear in-vehicle temperature sensor. see scheme 1 Measure resistance between sensor terminals at specified temperatures. See REAR IN-VEHICLE AIR TEMPERATURE SENSOR CIRCUIT RESISTANCE table. If resistance is not as specified, replace sensor.

REAR IN-VEHICLE AIR TEMPERATURE SENSOR CIRCUIT RESISTANCE

A/C Compressor Magnetic Clutch Control Circuit

1. Start and operate engine at 1500 RPM. Locate pressure switch in back of condenser and disconnect connector. Connect A/C manifold gauge set. Set blower control switch to highest speed. Turn A/C system on and set temperature control to cool position.
2. Connect negative ohmmeter lead to pressure switch terminal No. 1 (Blue/Black wire) and positive lead to No. 4 (White/Black wire). (Scheme 48) Observe refrigerant pressure and check for continuity between pressure switch terminals.
3. Continuity should exist as low-side pressure increases to more than 33 psi (2.3 kg/cm 2 ). Continuity should not exist as low-side pressure decreases to less than 28 psi (2.0 kg/cm 2 ).
4. Continuity should exist as high-side pressure decreases to less than 370 psi (26.0 kg/cm 2 ). Continuity should not exist as high-side pressure increases to more than 455 psi (32.0 kg/cm 2 ). If continuity is not as specified, replace pressure switch.

Scheme 48

Cooling Fan Control Circuit

1. Start and operate engine at 1500 RPM. Locate pressure switch in back of condenser and disconnect connector. Connect A/C manifold gauge set. Set blower control switch to highest speed. Turn A/C system on and set temperature control to cool position.
2. Connect positive ohmmeter lead to pressure switch terminal No. 2 (Black/Red wire) and negative lead to terminal No. 3 (White/Black wire). (Scheme 48) Observe refrigerant pressure and check for continuity between pressure switch terminals.
3. Continuity should exist as high-side pressure increases to more than 220 psi (15.5 kg/cm 2 ). Continuity should not exist as high-side pressure decreases to less than 178 psi (12.5 kg/cm 2 ). If continuity is not as specified, replace pressure switch.

Compressor Magnetic Clutch Relay

1. Remove compressor magnetic clutch relay, located in engine compartment relay block. Magnetic clutch relay is marked MG CLT. Continuity should exist between relay terminals No. 1 and 2. (Scheme 49) Continuity should not exist between relay terminals No. 3 and 5.
2. Using a fused jumper wire, connect battery voltage across relay terminals No. 1 and 2. Continuity should exist between relay terminals No. 3 and 5. Replace compressor magnetic clutch relay if continuity is not as specified.

Scheme 49

Condenser Fan Relay

Remove front bumper cover. Disconnect relay and remove. Continuity should exist between relay terminals No. 3 and 4. Continuity should not exist between relay terminals No. 1 and 2. (Scheme 50) Using a fused jumper wire, connect battery voltage across relay terminals No. 3 and 4. Continuity should exist between relay terminals No. 1 and 2. Replace condenser fan relay if continuity is not as specified.

Scheme 50

Front Blower Motor Control Relay

Remove blower motor control relay, leaving harness connector attached. (Scheme 51) Turn ignition on and operate blower motor at high speed. Backprobe blower motor control relay connectors and check for specified values. See TESTING BLOWER MOTOR CONTROL RELAY table. If test results are not as specified, replace blower motor control relay. If blower motor control relay is okay, repair wiring harness or connectors as necessary.

TESTING BLOWER MOTOR CONTROL RELAY

Scheme 51

Heater Main Relay

1. Remove heater main relay from right side cowl junction block, located behind passenger side kick panel. Continuity should exist between relay terminals No. 2 and 4, and between terminals No. 3 and 5. Continuity should not exist between relay terminals No. 1 and 2. (Scheme 52)
2. Using fused jumper wires, connect battery voltage across relay terminals No. 3 and 5. Continuity should exist between relay terminals No. 1 and 2. Replace heater main relay if continuity is not as specified.

Scheme 52

Rear Heater Main Relay

1. Remove rear heater relay, located behind driver kick panel, in No. 2 junction block. Continuity should exist between relay terminals No. 1 and 2. (Scheme 49) Continuity should not exist between relay terminals No. 3 and 5.
2. Using a fused jumper wire, connect battery voltage across relay terminals No. 1 and 2. Continuity should exist between relay terminals No. 3 and 5. Replace rear heater relay if continuity is not as specified.

SOLAR SENSOR

1. Remove solar sensor and disconnect sensor harness connector. see scheme 1 Connect positive lead of ohmmeter to sensor terminal No. 2 (Yellow/Black wire), and negative lead to terminal No. 1 (Green/Red wire). See «WIRING DIAGRAMS»(ref-98895-S36472759122001060500000).
2. Measure resistance between sensor terminals with sensor covered with a cloth. Uncover sensor and subject it to a bright light. Measure sensor resistance again. See «SOLAR SENSOR RESISTANCE SPECIFICATIONS»(ref-98895-S26639623812001072000000) table. If resistance is not as specified, replace sensor.

SOLAR SENSOR RESISTANCE SPECIFICATIONS

FRONT BLOWER MOTOR UNIT

Note. Blower motor and blower motor control relay can be removed without removing front blower motor unit.

REAR HEATER UNIT

1. Drain engine coolant until level is lower than rear heater core. Remove hoses from heater core pipes. Remove front seats. Remove rear console and front console box cover. Remove lower center cluster finish panel. (Scheme 53)
2. Remove front and rear door sill plates. Remove kick panels. Remove center pillar moldings. Slide carpet backward. Remove cooler bracket and rear heater duct. Disconnect connectors from rear heater unit. Remove rear heater unit.
3. Remove rear air mix damper control servomotor. Remove air inlet temperature sensor. Remove screws and heater core clamps. Remove "O" rings and discard. Remove heater core. Remove power transistor.
4. Remove blower motor cover. Separate heater unit case halves. Remove nut and blower fan (to access blower motor screws). Remove screws and rear blower motor. (Scheme 54) To install, reverse removal procedure. Install new "O" rings to heater core pipes.

Scheme 53

Scheme 54