HVAC System - Automatic: Other Honda Accord VI

AUTOMATIC CLIMATE CONTROL SYSTEM

The system uses a combination of heated and cooled air as necessary to achieve desired temperature. Temperatures can be selected from a maximum heating of 90°F (32°C) to a maximum cooling of 60°F (16°C). System uses a series of sensors to maintain selected in vehicle temperatures. Mode functions in FULL AUTO are automatically controlled by the climate control unit. Depending on desired temperature and efficiency factors, system also automatically selects fresh/recirculated (passenger compartment) air.

Manual operation of fresh/recirculated air is obtained by pressing appropriate button. Pressing defrost button directs treated air to windshield. System continues to control set temperature. Pressing AUTO button returns system to automatic operation. Pressing OFF button turns system off.

Automatic climate control contains self-diagnostic functions to help diagnose malfunctions in system using a series of Diagnostic Trouble Codes (DTCs).

CLIMATE CONTROL UNIT

When AUTO button is pressed, the automatic climate control system comes on and displays FULL AUTO. Temperature control dial allows temperature to be controlled in one degree increments from 60°F to 90°F (16-32°C). Liquid Crystal Display (LCD) displays current set temperature, A/C operation status and mode status. Driver can override systems default operating settings by pressing windshield, MODE or A/C buttons. FULL indicator on LCD display will turn off and AUTO will remain on. Full manual operation can be achieved by pressing OFF button then selecting mode, blower speed and temperature setting manually. (Scheme 28)

Scheme 28

SENSORS

The climate control unit automatically regulates vehicle interior temperature based on outside air temperature, engine coolant temperature, in-car temperature, and sunlight load. (Scheme 29)

Engine Coolant Temperature (ECT) Sensor

Sensor has a 2-wire connector (Red/White wire and Green/Black wire) and is located behind EGR valve on driver's side of engine. Climate control unit monitors ECT to determine if heat is available at heater core. If driver sets temperature above ambient temperature (ambient temperature approximately 50°F, set temperature at 75°F) but coolant is still cold, climate control will not operate fan until engine reaches operating temperature.

Evaporator Temperature Sensor

Sensor is located in evaporator case. Sensor monitors air temperature of air leaving evaporator core to help maintain set temperature.

In-Car Temperature Sensor

Sensor is located on driver's side of vehicle dash, just right of ignition lock cylinder. Sensor is a thermistor that monitors actual in-car temperature to maintain set temperature.

Outside (Ambient) Air Temperature Sensor

Sensor is located on radiator core support. Sensor monitors and compares ambient temperature to set temperature to determine if vent, A/C or heater operation is required to maintain set temperature.

Sunlight Sensor

Sensor is located in center of dash between defrost outlets. Sensor is a photodiode used to determine sunload on vehicle interior. If vehicle is in sunlight, system will increase cooling to compensate for increase in sunlight. If vehicle is in shade, system will decrease cooling.

POLLEN FILTERS

Vehicle is equipped with pollen filters to help reduce the amount of bacteria and small particles entering passenger compartment through A/C-heater system. These filters contain two separate filter elements. Filters are located in evaporator box and are replaceable. (Scheme 29) See A/C FILTERS under REMOVAL & INSTALLATION.

Scheme 29

HEATER VALVE CABLE

1. From engine compartment, open cable clamp and disconnect heater valve cable from heater valve arm. From air mix control motor disconnect heater cable housing from clamp and disconnect heater valve cable from air mix control linkage. (Scheme 30)
2. Turn ignition switch to ON position. Set temperature controls to maximum cooling on climate control unit.
3. Attach heater valve cable to air mix control linkage. Hold end of heater valve cable housing against stop and snap heater valve cable housing into clamp. (Scheme 30)
4. From engine compartment, turn heater valve arm to full closed position and hold. Attach heater valve cable to heater valve arm. Gently pull on heater valve cable to take up slack and install heater valve cable housing into clamp. Recheck operation of heater valve and cable.

Scheme 30

NO A/C & HEATER FUNCTIONS

1. Check fuse No. 3 (7.5-amp) in driver's underdash fuse/relay box and fuse No. 13 (7.5-amp) in underhood fuse/relay box. If fuses are blown, replace fuse(s). If necessary, repair short(s) to ground. If fuses are okay, go to next step.
2. Disconnect the climate control unit 8-pin connector. (Scheme 31) Turn ignition switch to ON position. Use a DVOM to measure voltage between ground and climate control unit 8-pin connector terminal No. 1 (Black/Yellow wire). If voltage does not exist, repair open Black/Yellow wire between fuse No. 3 and climate control unit 8-pin connector. If battery voltage exists, go to next step.
3. Turn ignition switch to OFF position. Use a DVOM to measure voltage between ground and climate control unit 8-pin connector terminal No. 2 (White/Yellow wire). If battery voltage does not exist, repair open White/Yellow wire between fuse No. 13 and climate control unit. If battery voltage exists, go to next step.
4. Turn ignition switch to OFF position. Use a DVOM to check for continuity between ground and climate control unit 8-pin connector terminal No. 8 (Black wire). If continuity exists, go to next step. If continuity does not exist, check for open Black wire between climate control unit and body ground. If wire is okay, check for poor ground connections.
5. Check for loose wires or poor connections at climate control unit 8-pin connector. If connections are okay, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit.

Scheme 31

RECIRCULATION CONTROL MOTOR DOES NOT OPERATE DOORS

1. Check fuse No. 3 (7.5-amp) in driver's underdash fuse/relay box. If fuse is blown, replace fuse. Repair short to ground if necessary. If fuse is okay, go to next step.
2. Disconnect recirculation control motor connector. Turn ignition to ON position. Use a DVOM to check for voltage between ground and recirculation control motor connector terminal No. 1 (Black/Yellow wire). If battery voltage does not exist, repair open in Black/Yellow wire between fuse No. 8 and recirculation control motor connector. If battery voltage exists, go to next step.
3. Turn ignition to OFF position. Test recirculation control motor. See «RECIRCULATION CONTROL MOTOR TESTING»(ref-35216-S34491557622001010900000). If motor is okay, go to next step. If motor is not okay, go to step 8.
4. Disconnect the climate control unit 20-pin connector. (Scheme 31) Use a DVOM to individually check for continuity between ground and climate control unit 20-pin connector terminal No. 4 (Green/White wire) and No. 3 (Green/Red wire). If continuity exists, repair shorted wire(s) between recirculation control motor and climate control unit. If continuity does not exist, go to next step.
5. Use a DVOM to individually check for voltage between ground and terminals No. 4 (Green/White wire) and No. 3 (Green/Red wire) of climate control unit 20-pin connector. If voltage exists, repair short to power in wire(s) between recirculation control motor and climate control unit. Climate control unit will be damaged by short and must be replaced after wire repair is made. If voltage does not exist, go to next step.
6. Use a DVOM to check for continuity in Green/White wire and Green/Red wire between recirculation control motor connector and climate control unit 20-pin connector. If continuity does not exist, repair open in wire(s) between recirculation control motor and climate control unit.
7. If continuity exists, check for loose wires or poor connections at climate control unit 20-pin connector and recirculation control motor connector. If connections are okay, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit.
8. Remove recirculation control motor. See procedures in «RECIRCULATION CONTROL MOTOR»(ref-35216-S33172592032001010900000). Check recirculation control linkage and doors for smooth operation. If linkage and doors are okay, replace recirculation control motor. If linkage and doors are not okay, repair control linkage and doors.

RADIATOR FAN DOES NOT RUN AT ALL, CONDENSER FAN OKAY

1. Check fuse No. 57 (20-amp) in underhood fuse/relay box. If fuse is blown, replace fuse. Repair short to ground if necessary. If fuse is okay, go to next step.
2. Remove radiator fan relay. Test radiator fan relay. See «RELAYS»(ref-35216-S07519165772001010900000) under TESTING. If radiator fan relay is faulty, replace radiator fan relay. If radiator fan relay is okay, go to next step.
3. Use a DVOM to check for battery voltage between ground and terminal No. 3 of radiator fan relay socket. If battery voltage does not exist, replace underhood fuse/relay box. If battery voltage exists, go to next step.
4. Connect a fused jumper wire between terminals No. 1 (White wire) and No. 3 (Yellow wire) of radiator fan relay socket. If radiator fan runs, go to next step. If radiator fan does not run, go to step 6 .
5. Disconnect jumper wire. Turn ignition on. Use a DVOM to check for battery voltage between ground and radiator fan relay socket terminal No. 3 (Yellow wire). If battery voltage exists, go to step 8 . If battery voltage does not exist, repair open in Black/Yellow wire between underhood fuse/relay box and driver's underdash fuse/relay box.
6. Turn ignition switch to OFF position. Disconnect radiator fan connector. Use a DVOM to check for continuity in Blue/Black wire between radiator fan relay connector terminal No. 2 and radiator fan connector terminal No. 2. If continuity does not exist, repair open Blue/Black wire between radiator fan relay and radiator fan. If continuity does exist, go to next step.
7. Use a DVOM to check for continuity between ground and radiator fan connector terminal No. 1 (Black wire). If continuity is indicated, go to next step. Check for open in Black wire between radiator fan connector terminal No. 1 and ground. If wire is okay, repair ground for switch.
8. Reinstall radiator fan relay. Disconnect radiator fan switch connector. Use a fused jumper wire between both connector terminals. If fan runs, replace radiator fan switch. If fan does not run, go to next step.
9. Turn ignition to ON position. Remove fused jumper wire. Use a DVOM to check for voltage between ground and radiator fan switch connector terminal No. 2 (Green wire). If battery voltage is indicated, check for open in Black wire between radiator fan switch connector and ground. If wire is okay, repair ground for switch. If battery voltage is not indicated, repair open in Green wire between radiator fan switch connector and underhood fuse/relay box.

CONDENSER FAN DOES NOT COME ON, RADIATOR FAN OKAY

1. Check fuse No. 58 (20-amp) in underhood fuse/relay box and fuse No. 3 (7.5-amp) in driver's underdash fuse/relay box. If fuse is blown, replace fuse. Repair short to ground if necessary. If fuse is okay, go to next step.
2. Remove condenser fan relay from underhood fuse/relay box. Test condenser fan relay. See «RELAYS»(ref-35216-S07519165772001010900000) under TESTING. If condenser fan relay is okay, go to next step. If condenser fan relay is not okay, replace relay.
3. Use a DVOM to check for voltage between ground and condenser fan relay connector terminal No. 1 (White wire). If battery voltage does not exist, replace underhood fuse/relay box. If battery voltage exists, go to next step.
4. Connect a fused jumper wire between condenser fan relay connector terminal No. 2 (Blue/Yellow wire) and terminal No. 1 (White wire terminal). If condenser fan runs, go to next step. If condenser fan does not run, go to step 7 .
5. Disconnect jumper wire. Turn ignition switch to ON position. Use a DVOM to measure voltage between ground and condenser fan relay connector terminal No. 3 (Yellow/White wire). If battery voltage is indicated, replace underhood fuse/relay box. If battery voltage is not indicated, go to next step.
6. With radiator fan control module connected, use a DVOM to check for voltage between terminal No. 3 and ground. If battery voltage is indicated, repair open in Yellow/White wire between condenser fan relay and radiator fan module. If battery voltage is not indicated, go to «RADIATOR FAN CONTROL MODULE»(ref-35216-S36336878312001010900000) under TESTING.
7. Disconnect fused jumper wire. Disconnect condenser fan connector. Use a DVOM to check for continuity in Blue/Yellow wire between condenser fan relay connector terminal No. 2 and condenser fan connector. If continuity does not exist, repair open in Blue/Yellow wire between condenser fan relay and condenser fan. If continuity exists, go to next step.
8. Use a DVOM to check for continuity between ground and Black wire terminal of condenser fan connector. If continuity exists, replace condenser fan motor. If continuity does not exist, check for open in Black wire between ground and condenser fan. If Black wire is okay, check for poor ground connection.

FANS COME ON WHEN A/C IS ON, BUT NOT FOR ENGINE COOLING

1. Disconnect radiator fan switch connector. Turn ignition switch to ON position. Use a DVOM to check for voltage between ground and radiator fan switch connector terminal No. 2 (Green wire). If battery voltage is indicated, go to next step. If battery voltage is not indicated, repair open in Green wire between radiator fan switch connector terminal No. 2 and underhood fuse/relay box.
2. Turn ignition switch to OFF position. Use a DVOM to check for continuity between radiator fan switch connector terminal No. 1 and ground (Black wire). If continuity is indicated, go to next step. If continuity is not indicated, check for open in Black wire between radiator fan switch and ground. If wire is okay, repair ground for switch.
3. Check cooling system. If cooling system is okay and within operating temperatures, replace radiator fan switch. If problem in cooling system exists, repair cooling system.

NEITHER FAN COMES ON

1. Check fuse No. 57 (20-amp) and fuse No. 58 (20-amp) in driver's underdash fuse/relay box. If fuse is blown, replace fuse(s). Repair short to ground if necessary. If fuse is okay, go to next step.
2. Remove condenser fan relay from underhood fuse/relay box. Turn ignition switch to ON position. With radiator fan control module connector connected, use a DVOM to check for voltage between ground and radiator fan control module connector terminal No. 3 (Yellow/White wire).
3. If battery voltage does not exist, test radiator fan control module. See «RADIATOR FAN CONTROL MODULE»(ref-35216-S36336878312001010900000) under TESTING. If battery voltage exists, go to next step.
4. Turn ignition switch to OFF position. Reinstall radiator fan relay in underhood fuse/relay box. Verify A/C switch is in OFF position. Turn ignition switch to ON position.
5. Using Backprobe Set (07SAZ-001000A), check for voltage between ground and Powertrain Control Module (PCM) 32-pin connector terminal No. 20. (Scheme 32) If battery voltage is indicated, check for loose wires or poor connections at PCM connector. If connections are okay, substitute a known-good PCM and recheck. If symptom goes away, replace original PCM.

Scheme 32

A/C COMPRESSOR CLUTCH DOES NOT ENGAGE

1. Check fuse No. 58 (20-amp) in underhood fuse/relay box, and fuse No. 3 (7.5-amp) in underdash fuse/relay box. If fuse is blown, replace fuse(s). Repair short to ground if necessary. If fuses are okay, go to, next step.
2. Check engine coolant temperature. If coolant temperature is above normal, repair overheating problem before proceeding with trouble shooting. If coolant temperature is okay, go to next step.
3. Remove compressor clutch relay. Test compressor clutch relay. See «RELAYS»(ref-35216-S07519165772001010900000) under TESTING. If compressor clutch relay is okay, go to next step. If relay is not okay, replace relay.
4. Use a DVOM to check for voltage between ground and compressor clutch relay connector terminal No. 1 (White wire). If battery voltage does not exist, replace underhood fuse/relay box. If battery voltage exists, go to next step.
5. Connect a fused jumper wire between compressor clutch relay connector terminal No. 2 (Red wire) and terminal No. 1 (White wire). If compressor clutch engages, go to next step. If compressor clutch does not engage, go to step 9.
6. Disconnect fused jumper wire. Turn ignition switch to ON position. Use a DVOM to check for voltage between ground and compressor clutch relay connector terminal No. 4 (Black/Yellow wire). If battery voltage does not exist, repair open Black/Yellow wire between fuse No. 3 and compressor clutch relay connector terminal No. 4. If battery voltage exists, go to next step.
7. Turn ignition switch to OFF position. Reinstall compressor clutch relay. Verify A/C switch is off. Turn ignition switch to ON position. Using Backprobe Set (07SAZ-001000A), with PCM connected check for voltage between ground and terminal No. 17 (Red wire) of PCM 32-pin connector. (Scheme 32)
8. If battery voltage does not exist, repair open Red wire between compressor clutch relay and PCM. If battery voltage is indicated, check for loose wires or poor connections at PCM 32-pin connector. If connections are okay, substitute known-good PCM and recheck. If battery voltage does not exist after substituting known-good PCM, replace original PCM.
9. Disconnect fused jumper wire. Disconnect compressor clutch connector. Use a DVOM to check for continuity between compressor clutch relay connector terminal No. 2 and compressor clutch connector (Red wire). If continuity does not exist, repair open in Red wire between compressor clutch relay and compressor clutch.
10. If continuity exists, check compressor clutch clearance. Clearance should be.014-.026" (.36-.66 mm) and clutch coil resistance should be 3.4-3.8 ohms at 68°F (20°C). If clearance is okay, or if coil resistance is not to specification, replace compressor clutch coil.

A/C SYSTEM DOES NOT OPERATE

1. Disconnect A/C pressure switch connector. Turn ignition switch to ON position. Use a DVOM to measure voltage between ground and A/C pressure switch connector terminal No. 2 (Blue/Red wire). If reading is approximately 5 volts, go to next step. If reading is not approximately 5 volts, go to step 5.
2. Turn ignition switch to OFF position. Use a DVOM to check for continuity between terminals of A/C pressure switch. If continuity is indicated, go to next step. If continuity is not indicated, go to step 6.
3. Reconnect A/C pressure switch connector. Disconnect climate control unit 20-pin connector. (Scheme 31) Turn ignition to ON position. Use a DVOM to measure voltage between ground and climate control unit connector terminal No. 2 (Yellow/Green wire). If reading is approximately 5 volts, check for loose wires or poor connections at climate control unit 20-pin connector and A/C pressure switch connector.
4. If connections are okay, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit. If reading is not approximately 5 volts, repair open in Yellow/Green wire between climate control unit 20-pin connector and A/C pressure switch connector.
5. Using Backprobe Set (07SAZ-001000A), check for voltage between ground and Powertrain Control Module (PCM) 32-pin connector terminal No. 20. (Scheme 32) If battery voltage is indicated, check for loose wires or poor connections at PCM connector. If connections are okay, substitute a known-good PCM and recheck. If symptom goes away, replace original PCM. See «POWERTRAIN CONTROL MODULE (PCM)»(ref-35216-S19446081102001010900000) under REMOVAL & INSTALLATION. If battery voltage is not indicated, repair open in Blue/Red wire between PCM 32-pin connector and A/C pressure switch connector.
6. Check system for proper A/C pressures. If pressure is within specifications, replace A/C pressure switch. If pressure is not within specifications, repair A/C system.

CODE A: IN-CAR TEMPERATURE SENSOR OPEN CIRCUIT

1. Check in-car temperature sensor. See «IN-CAR TEMPERATURE SENSOR TESTING»(ref-35216-S16144276372001010900000). If readings are within specifications, go to next step. If readings are not within specifications, replace in-car temperature sensor.
2. Disconnect the climate control unit 20-pin connector. (Scheme 31) Use a DVOM to check for continuity of Yellow/Red wire between climate control unit 20-pin connector terminal No. 16 and in-car temperature sensor connector terminal No. 2. If continuity is indicated, go to next step. If continuity is not indicated, repair open Yellow/Red wire.
3. Use a DVOM to check for continuity of Yellow/Green wire between climate control unit 20-pin connector terminal No. 11 and in-car temperature sensor connector terminal No. 1. If continuity is indicated, check for loose connections at sensor and climate control unit.
4. If connections are okay, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit. If continuity is not indicated, repair open in Yellow/Green wire.

CODE B: IN-CAR TEMPERATURE SENSOR SHORT CIRCUIT

1. Check in-car temperature sensor. See «IN-CAR TEMPERATURE SENSOR TESTING»(ref-35216-S16144276372001010900000). If readings are within specifications, go to next step. If readings are not within specifications, replace in-car temperature sensor.
2. Disconnect the climate control unit 20-pin connector. (Scheme 31) Use a DVOM to check for continuity of Yellow/Red wire between climate control unit 20-pin connector terminal No. 16 and ground.
3. If continuity is indicated, Repair short to ground in Yellow/Red wire between climate control unit 20-pin connector terminal No. 16 and sensor. If continuity is not indicated, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit.

CODE C: OUTSIDE (AMBIENT) AIR TEMP SENSOR OPEN CIRCUIT

1. Check outside temperature sensor. See «OUTSIDE AIR TEMPERATURE SENSOR TESTING»(ref-35216-S00899846912001010900000). If readings are within specifications, go to next step. If readings are not within specifications, replace outside temperature sensor.
2. Disconnect the climate control unit 20-pin connector. (Scheme 31) Use a DVOM to check for continuity of Brown/White wire between climate control unit 20-pin connector terminal No. 15 and outside temperature sensor connector terminal No. 1. If continuity is indicated, go to next step. If continuity is not indicated, repair in open Brown/White wire.
3. Use a DVOM to check for continuity of Yellow/Green wire between climate control unit 20-pin connector terminal No. 11 and outside temperature sensor connector terminal No. 2. If continuity is indicated, check for loose connections at sensor and climate control unit.
4. If connections are okay, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit. If continuity is not indicated, repair open in Yellow/Green wire.

CODE D: OUTSIDE (AMBIENT) AIR TEMP SENSOR OPEN CIRCUIT

1. Check OUTSIDE TEMPERATURE SENSOR. See «OUTSIDE AIR TEMPERATURE SENSOR TESTING»(ref-35216-S00899846912001010900000). If readings are within specifications, go to next step. If readings are not within specifications, replace outside temperature sensor.
2. Disconnect the climate control unit 20-pin connector. (Scheme 31) Use a DVOM to check for continuity of Brown/White wire between climate control unit 20-pin connector terminal No. 15 and ground. If continuity is indicated, repair short to ground in Brown/White wire between climate control unit 20-pin connector terminal No. 15 and sensor.
3. If continuity is not indicated, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit.

CODE E: SUNLIGHT SENSOR OPEN CIRCUIT

1. Disconnect sunlight sensor connector. Disconnect climate control unit 20-pin connector. (Scheme 31) Use a DVOM to check for continuity in White/Red wire between climate control unit 20-pin connector terminal No. 12 and sensor connector terminal No. 1. If continuity is not indicated, repair open in White/Red wire between climate control unit and sunlight sensor.
2. If continuity is indicated, use a DVOM to check for continuity in Yellow/Green wire between climate control unit 20-pin connector terminal No. 11 and sensor connector. If continuity is indicated, go to next step. If continuity is not indicated, repair open in Yellow/Green wire between climate control unit and sunlight sensor.
3. Reconnect sunlight sensor connector. Reconnect climate control unit 20-pin connector. Test sunlight sensor. See procedures in «SUNLIGHT SENSOR TESTING»(ref-35216-S09253868582001010900000). If readings are within specifications, check for loose connections at sensor and climate control unit.
4. If connections are okay, substitute known-good climate control unit and recheck system. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit. If readings are not within specifications, replace sunlight sensor.

CODE F: SUNLIGHT SENSOR SHORT CIRCUIT

1. Disconnect sunlight sensor connector. Disconnect climate control unit 20-pin connector. (Scheme 31) Use a DVOM to check for continuity in White/Red wire between climate control unit 20-pin connector terminal No. 12 and ground. If continuity is indicated, repair short in White/Red wire between climate control unit and sunlight sensor.
2. If continuity is not indicated, reconnect sunlight sensor and climate control unit connectors. Turn ignition switch to ON position. Use a DVOM and backprobe to measure voltage between sunlight sensor connector terminals (Red DVOM lead to White/Red wire terminal and Black lead to Yellow/Green wire terminal).
3. Completely cover sensor from sunlight. Reading should be 3.7 volts or greater. Uncover sensor. Reading should be 3.6 volts or less. If readings are within specifications, check for loose connections at sensor and climate control unit.
4. If connections are okay, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit. If readings are not within specifications, replace sunlight sensor.

CODE G: EVAPORATOR TEMPERATURE SENSOR OPEN CIRCUIT

1. Check evaporator temperature sensor. See procedures in «EVAPORATOR TEMPERATURE SENSOR TESTING»(ref-35216-S22427697802001010900000). If readings are within specification, go to next step. If readings are not within specifications, replace evaporator temperature sensor.
2. Disconnect the climate control unit 20-pin connector. (Scheme 31) Use a DVOM to check for continuity of Brown wire between climate control unit 20-pin connector terminal No. 14 and evaporator temperature sensor connector terminal No. 2. If continuity is indicated, go to next step. If continuity is not indicated, repair open in Brown wire.
3. Use a DVOM to check for continuity of Yellow/Green wire between climate control unit 20-pin connector terminal No. 11 and evaporator temperature sensor connector terminal No. 1. If continuity is indicated, check for loose connections at sensor and climate control unit.
4. If connections are okay, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit. If continuity is not indicated, repair open in Yellow/Green wire.

CODE H: EVAPORATOR TEMPERATURE SENSOR SHORT CIRCUIT

1. Check evaporator temperature sensor. See procedures in «EVAPORATOR TEMPERATURE SENSOR TESTING»(ref-35216-S22427697802001010900000). If readings are within specification, go to next step. If readings are not within specifications, replace evaporator temperature sensor.
2. Disconnect the climate control unit 20-pin connector. (Scheme 31) Use a DVOM to check for continuity of Brown wire between climate control unit 20-pin connector terminal No. 14 and ground. If continuity is indicated, Repair short to ground in Brown wire between climate control unit connector terminal No. 14 and sensor.
3. If continuity is not indicated, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit.

CODE I: AIR MIX CONTROL MOTOR OPEN CIRCUIT

1. Disconnect air mix control motor connector. Disconnect climate control unit 20-pin connector. (Scheme 31) Use a DVOM to check for continuity between following climate control unit 20-pin connector terminals and air mix control motor connector terminals. See «AIR MIX CONTROL MOTOR CIRCUIT CONTINUITY»(ref-35216-S16930134792001010900000) table.
2. If continuity is indicated, check for loose connections at sensor and climate control unit. If connections are okay, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit. If continuity is not indicated, repair open in suspect wire.

AIR MIX CONTROL MOTOR CIRCUIT CONTINUITY

CODE J: AIR MIX CONTROL MOTOR SHORT CIRCUIT

1. Disconnect air mix control motor connector. Disconnect climate control unit 20-pin connector. (Scheme 31) Use a DVOM to check for continuity between ground and climate control unit 20-pin connector terminals No. 1, 7, 9, 11, and 13. If continuity exist, repair short in suspect wire. If continuity does not exist, go to next step.
2. Turn ignition switch to ON position. Use a DVOM to check for voltage between ground and climate control unit 20-pin connector terminals No. 1, 7, 9, 11, and 13. If voltage is indicated, repair short to power in suspect wire. Short to power will damage climate control unit, repair short before replacing climate control unit.
3. If no voltage is indicated, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit.

CODE K: AIR MIX CONTROL MOTOR MECHANICAL FAILURE

1. Test air mix control motor. See «AIR MIX CONTROL MOTOR TESTING»(ref-35216-S26226456822001010900000) . If air mix control motor does not test okay, go to next step. If air mix control motor tests okay, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit.
2. Remove air mix motor. See «AIR MIX CONTROL MOTOR»(ref-35216-S00261116492001010900000) under REMOVAL & INSTALLATION. Check air mix door for binding, missing linkage or broken parts. If air mix door works smoothly, replace air mix control motor. If air mix door does not move smoothly, repair door mechanism as necessary.

CODE L: MODE CONTROL MOTOR OPEN/SHORT CIRCUIT

1. Disconnect air mix control motor connector. Disconnect climate control unit 20-pin connector. (Scheme 31) Use a DVOM to check for continuity between ground and climate control unit 20-pin connector terminals No. 5, 6, 11, 17, 18, 19 and 20. If continuity is indicated, repair short in suspect wire. If continuity is not indicated, go to next step.
2. Turn ignition switch to ON position. Use a DVOM to check for voltage between ground and climate control unit 20-pin connector terminals No. 5, 6, 11, 17, 18, 19 and 20. If voltage is indicated, repair short to power in suspect wire. Short to power will damage climate control unit, repair short before replacing climate control unit. If voltage is not indicated, go to next step.
3. Turn ignition switch to OFF position. Use a DVOM to check for continuity between following climate control unit 20-pin connector and mode control motor connector. See «MODE CONTROL MOTOR CIRCUIT CONTINUITY»(ref-35216-S09168482862001010900000) table. If continuity is indicated, check for loose connections at sensor and climate control unit.
4. If connections are okay, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit. If continuity is not indicated, repair open in suspect wire.

MODE CONTROL MOTOR CIRCUIT CONTINUITY

CODE M: MODE CONTROL MOTOR MECHANICAL FAILURE

1. Test mode control motor. See «MODE CONTROL MOTOR TESTING»(ref-35216-S38268866882001010900000) . If mode control motor tests okay, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit.
2. If mode control motor does not test okay, remove mode control motor. See «MODE CONTROL MOTOR»(ref-35216-S20429955072001010900000) . Check mode door for binding, missing linkage or broken parts. If mode door works smoothly, replace mode control motor. If mode door does not move smoothly, repair mode door mechanism as necessary.

Blower Motor Runs At High Speed Only

1. Disconnect power transistor connector. Use a DVOM to check for continuity between ground and power transistor connector terminal No. 4 (Black wire). If continuity exists, go to step 3.
2. If continuity does not exists, check for open in Black wire between power transistor and ground. If circuit is okay, check for poor ground to power transistor.
3. Connect a fused jumper wire between power transistor connector terminals No. 3 and 4. Turn ignition switch to ON position. If blower motor runs at high speed, go to next step. If blower motor does not run at high speed, repair open in Blue/Red wire between power transistor and blower motor.
4. Turn ignition switch to OFF position. Disconnect fused jumper wire. Disconnect the climate control unit 8-pin connector. (Scheme 31) Use a DVOM to check for continuity between climate control unit 8-pin connector terminal No. 5 and power transistor connector terminal No. 2 (Orange/Black wire). If continuity exists, go to next step. If continuity does not exists, repair open in Orange/Black wire between power transistor and climate control unit.
5. Use a DVOM to check for continuity between ground and climate control unit 8-pin connector terminal No. 5. If continuity exists, repair short in Orange/Black wire between power transistor and climate control unit. If continuity does not exist, go to next step.
6. Use a DVOM to check for continuity between climate control unit 8-pin connector terminal No. 6 and power transistor connector terminal No. 1. If continuity exists, go to next step. If continuity does not exists, repair open in Blue/Red wire between power transistor and climate control unit.
7. Reconnect climate control unit 8-pin connector. Test power transistor. See «POWER TRANSISTOR»(ref-35216-S04804179092001010900000) under TESTING. If blower motor runs, check for loose connections at power transistor and climate control unit. If connections are okay, substitute with known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit. If blower motor does not run, replace power transistor. Recheck blower motor operation.

Blower Motor Inoperative In All Speeds

1. Check fuse No. 56 in underhood fuse/relay box (located right rear of engine compartment) and fuse No. 3 in driver's underdash fuse/relay box. If either fuse is open, replace fuse(s) and recheck blower motor operation.
2. If fuses are okay, use a fused jumper wire to connect blower motor connector terminal No. 2 to ground. Turn ignition switch to ON position. If blower motor runs, go to next step. If blower motor does not run, go to step 9.
3. Turn ignition switch to OFF position. Disconnect fuse jumper wire. Test blower motor high relay. See «RELAYS»(ref-35216-S07519165772001010900000) under TESTING. If relay checks out okay, go to next step. If relay is not okay, replace blower motor high relay.
4. Use a fused jumper wire to connect blower motor high relay connector terminal No. 3 to ground. Turn ignition switch to ON position. If blower motor runs, go to next step. If blower motor does not run, repair open in Blue/Red wire between blower motor and blower motor high relay.
5. Turn ignition switch to OFF position. Disconnect fused jumper wire. Turn ignition switch to ON position. Use a DVOM to check for voltage between ground and blower motor high relay connector terminal No. 1. If battery voltage is indicated, go to next step. If battery voltage is not indicated, repair open in Black/Yellow wire between blower motor high relay and fuse No. 3 in driver's underdash fuse/relay box.
6. Turn ignition switch to OFF position. Use a DVOM to check for continuity between ground and blower motor high relay connector terminal No. 4. If continuity is indicated, go to next step. If continuity is not indicated, repair open in Black wire between blower motor high relay and ground.
7. Disconnect the climate control unit 20-pin connector. (Scheme 31) Use a DVOM to check for continuity between climate control unit 20-pin connector terminal No. 4 and blower motor high relay connector terminal No. 2 (Blue/Orange wire). If continuity is indicated, check for loose connections at blower motor high relay and climate control unit.
8. If connections are okay, substitute with known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit. If continuity does not exist, repair open in Blue/Orange wire between climate control unit and blower motor high relay.
9. Disconnect fused jumper wire. Disconnect blower motor connector. Use a DVOM to check for voltage between ground and blower motor connector terminal No. 1. If battery voltage is indicated, replace blower motor. If battery voltage is not indicated, go to next step.
10. Turn ignition switch to OFF position. Remove blower motor relay from underhood fuse/relay box. Use a DVOM to check relay. Continuity should exist between blower motor high relay terminals No. 1 and 3 when power and ground are connected to terminals No. 2 and 4. Relay should be open at terminals No. 1 and 3 when power is not applied. If relay checks out okay, go to next step. If relay is not okay, replace blower motor relay.
11. Use a DVOM to check for voltage between ground and blower motor relay connector terminal No. 4. If battery voltage is indicated, go to next step. If battery voltage is not indicated, replace underhood fuse/relay box.
12. Turn ignition switch to ON position. Use a DVOM to check for voltage between ground and blower motor relay connector terminal No. 1. If battery voltage is indicated, go to next step. If battery voltage is not indicated, repair open in Yellow/Black wire between blower motor relay and underhood fuse/relay box.
13. Turn ignition switch to OFF position. Use a DVOM to check for continuity between ground and blower motor relay connector terminal No. 2. If continuity is indicated, repair open in Yellow/Black wire between blower motor and blower motor relay in underhood fuse/relay box. If continuity is not indicated, check for open in Black wire between blower motor relay and ground. If wire is okay, check for poor ground at body from blower motor relay.

A/C SYSTEM PERFORMANCE

1. Park vehicle out of direct sunlight. Open engine hood. Open front doors. Connect A/C pressure gauges to pressure ports. Measure relative humidity. Measure ambient air temperature.
2. Move temperature control lever to coldest setting. Select vent mode. Select recirculated air. Insert a thermometer in center vent outlet. Turn A/C switch on, and set blower switch to highest speed. Run engine at 1500 RPM. Ensure no one is inside vehicle.
3. After running A/C for 10 minutes, check temperature at center vent outlet. Check system pressures. Identify vehicle condenser. If temperature and pressures match A/C system performance test chart for specified condenser, system is operating within range. (Scheme 33)and (Scheme 34) or (Scheme 35).

Scheme 33

Scheme 34

Scheme 35

ENGINE COOLANT TEMPERATURE SENSOR

1. Check Malfunction Indicator Light (MIL). If light comes on, see TESTS W/CODES article in ENGINE PERFORMANCE. If light does not come on, go to next step.
2. Turn ignition off. Disconnect climate control unit 8-pin connector. (Scheme 31) Disconnect engine coolant temperature sensor connector. Turn ignition switch to ON position.
3. Use a DVOM to measure voltage between ground and climate control 8-pin connector terminal No. 3 (Red/White wire). If DVOM does not indicate approximately 5 volts, repair open in Red/White wire between climate control unit 8-pin connector and engine coolant temperature sensor.
4. If DVOM indicates approximately 5 volts, check for loose wires or poor connections at climate control unit 8-pin connector and engine coolant temperature sensor. If connections are okay, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit.

POWER TRANSISTOR

1. Disconnect power transistor connector. Use a DVOM to measure resistance between power transistor terminal No. 1 and 3. Resistance should be 1.5 k/ohms. Carefully remove terminal No. 2 (Orange/Black wire) from power transistor connector.
2. Using a 1.2-3.4 watt bulb, probe power transistor connector terminals No. 2 and 3. (Scheme 36) Reconnect power transistor connector. Turn ignition switch to ON position. Blower motor should run.

Scheme 36

RADIATOR FAN CONTROL MODULE

Perform test with radiator fan control module connector connected, ignition on and A/C switch OFF. (Scheme 37) Also, refer to the RADIATOR FAN CONTROL MODULE INPUT TESTS table. If cause of problem is discovered while performing tests, correct problem before continuing tests.

Scheme 37

RADIATOR FAN CONTROL MODULE INPUT TESTS

RELAYS

Remove suspect relay. Use a DVOM to check relay. Continuity should exist between blower motor high relay terminals No. 1 and 3 when power/ground are connected to terminals No. 2 and 4. (Scheme 38), (Scheme 39) or (Scheme 40). Relay should be open at terminals No. 1 and 3 when power is not applied.

Scheme 38

Scheme 39

Scheme 40

COMPRESSOR

Note. If possible, run engine at idle with A/C on for about 2 minutes before removing compressor.

COMPRESSOR CLUTCH & FIELD COIL

Note. Required Tools: A/C clutch holder, Robinair 10204, Kent-Moore J37872, or Honda Tool and Equipment KMT-J33939.