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Home >> Lexus >> 2006 >> RX 400h FWD >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Air Conditioning >> Air Conditioning System >> Problem Symptoms Table

Problem Symptoms Table

Air Conditioning System 

AIR CONDITIONING SYSTEM PROBLEM SYMPTOMS

Symptom Suspected area
Entire A/C system does not operate 1. IG POWER SOURCE CIRCUIT 
2. A/C amplifier assembly. See REMOVAL 
Air Flow Control: No blower operation 1. HEATER RELAY CIRCUIT 
2. BLOWER MOTOR CIRCUIT 
3. A/C amplifier assembly. See REMOVAL 
Air Flow Control: No blower control 1. HEATER RELAY CIRCUIT 
2. BLOWER MOTOR CIRCUIT 
3. A/C amplifier assembly. See REMOVAL 
Air Flow Control: Insufficient air output 1. BLOWER MOTOR CIRCUIT 
2. A/C amplifier assembly. See REMOVAL 
Temperature Control: No cool air comes out 1. VOLUME OF REFRIGERANT 
2. REFRIGERANT PRESSURE 
3. PRESSURE SWITCH CIRCUIT 
4. AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT (DRIVER SIDE) 
5. AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT (PASSENGER SIDE) 
6. AIR MIX DAMPER POSITION SENSOR CIRCUIT (DRIVER SIDE) 
7. AIR MIX DAMPER POSITION SENSOR CIRCUIT (PASSENGER SIDE) 
8. ROOM TEMPERATURE SENSOR CIRCUIT .
9. ROOM HUMIDITY SENSOR CIRCUIT 
10. AMBIENT TEMPERATURE SENSOR CIRCUIT 
11. EVAPORATOR TEMPERATURE SENSOR CIRCUIT 
12. A/C amplifier assembly. See REMOVAL 
13. Multiplex communication circuit. See HOW TO PROCEED WITH TROUBLESHOOTING
Temperature Control: No warm air comes out 1. HEATER RELAY CIRCUIT 
2. HEATER WATER PUMP CIRCUIT 
3. AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT (DRIVER SIDE) 
4. AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT (PASSENGER SIDE) 
5. AIR MIX DAMPER POSITION SENSOR CIRCUIT (DRIVER SIDE) 
6. AIR MIX DAMPER POSITION SENSOR CIRCUIT (PASSENGER SIDE) 
7. ROOM TEMPERATURE SENSOR CIRCUIT 
8. ROOM HUMIDITY SENSOR CIRCUIT 
9. AMBIENT TEMPERATURE SENSOR CIRCUIT 
10. EVAPORATOR TEMPERATURE SENSOR CIRCUIT 
11. Heater radiator unit sub-assembly. See DISASSEMBLY 
12. A/C amplifier assembly. See REMOVAL 
13. Multiplex communication circuit. See HOW TO PROCEED WITH TROUBLESHOOTING
Temperature Control: Output air is warmer or cooler than set temperature or response is slow 1. VOLUME OF REFRIGERANT 
2. REFRIGERANT PRESSURE 
3. AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT (DRIVER SIDE) 
4. AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT (PASSENGER SIDE) 
5. AIR MIX DAMPER POSITION SENSOR CIRCUIT (DRIVER SIDE) 
6. AIR MIX DAMPER POSITION SENSOR CIRCUIT (PASSENGER SIDE) 
7. ROOM TEMPERATURE SENSOR CIRCUIT 
8. ROOM HUMIDITY SENSOR CIRCUIT 
9. AMBIENT TEMPERATURE SENSOR CIRCUIT 
10. SOLAR SENSOR CIRCUIT (DRIVER SIDE) 
11. SOLAR SENSOR CIRCUIT (PASSENGER SIDE) 
12. Expansion valve. See DISASSEMBLY 
13. Heater radiator unit sub-assembly. See DISASSEMBLY 
14. A/C amplifier assembly. See REMOVAL 
15. Multiplex communication circuit. See HOW TO PROCEED WITH TROUBLESHOOTING
Temperature Control: No temperature control (only Max. cool or Max. warm) 1. ROOM TEMPERATURE SENSOR CIRCUIT 
2. ROOM HUMIDITY SENSOR CIRCUIT 
3. AMBIENT TEMPERATURE SENSOR CIRCUIT 
4. AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT (DRIVER SIDE) 
5. AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT (PASSENGER SIDE) 
6. AIR MIX DAMPER POSITION SENSOR CIRCUIT (DRIVER SIDE) 
7. AIR MIX DAMPER POSITION SENSOR CIRCUIT (PASSENGER SIDE) 
8. A/C amplifier assembly. See REMOVAL 
No air inlet control 1. AIR INLET DAMPER CONTROL SERVOMOTOR CIRCUIT 
2. AIR INLET DAMPER POSITION SENSOR CIRCUIT 
3. A/C amplifier assembly. See REMOVAL 
No air outlet control 1. AIR OUTLET DAMPER CONTROL SERVOMOTOR CIRCUIT 
2. AIR OUTLET DAMPER POSITION SENSOR CIRCUIT 
3. A/C amplifier assembly. See REMOVAL 
Engine idle does not occur, or is continuous 1. A/C amplifier assembly. See REMOVAL 
2. Multiplex communication circuit. See HOW TO PROCEED WITH TROUBLESHOOTING
Displayed set temperature value does not match with operation of temperature control switch 1. A/C amplifier assembly. See REMOVAL 
Brightness does not change when rheostat volume or light control 1. Illumination light system
2. A/C amplifier assembly. See REMOVAL 
Unable to access the diagnosis mode 1. A/C amplifier assembly. See REMOVAL 
DTC is not recorded. Set mode is cleared when IG switch is turned off. 1. BACK-UP POWER SOURCE CIRCUIT 
2. A/C amplifier assembly. See REMOVAL 
Unable to control A/C with the multi-display 1. Multiplex communication circuit. See HOW TO PROCEED WITH TROUBLESHOOTING
2. Multi-display assembly (w/ Navigation System). See MULTI-DISPLAY
3. Integration control & panel assembly (w/o Navigation System). See REMOVAL 
4. A/C amplifier assembly. See REMOVAL