Problem Symptoms Table
WARNING: This page is about a different car, the 2007 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.
HINT:
Use the table below to help determine the cause of the problem symptom. The potential causes of the symptoms are listed in order of probability in the "Suspected area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
Air conditioning system
PROBLEM SYMPTOMS CHART
| Symptom | Suspected area | See |
|---|---|---|
| Whole functions of the A/C system do not operate | 1. IG power source circuit | IG POWER SOURCE CIRCUIT |
| 2. A/C amplifier (A/C control) | TERMINALS OF ECU | |
| Air Flow Control: No blower operation | 1. Blower motor circuit | BLOWER MOTOR CIRCUIT |
| 2. A/C amplifier (A/C control) | TERMINALS OF ECU | |
| Air Flow Control: No blower control | 1. Blower motor circuit | BLOWER MOTOR CIRCUIT |
| 2. A/C amplifier (A/C control) | TERMINALS OF ECU | |
| Air Flow Control: Insufficient air output | 1. Blower motor circuit | BLOWER MOTOR CIRCUIT |
| 2. A/C amplifier (A/C control) | TERMINALS OF ECU | |
| Temperature Control: No cool air comes out | 1. Volume of refrigerant | REFRIGERANT |
| 2. Drive belt tension | REMOVAL | |
| 3. Refrigerant pressure | REFRIGERANT | |
| 4. Compressor circuit | COMPRESSOR CIRCUIT | |
| 5. Compressor lock sensor circuit | DTC B1422/22 Compressor Lock Sensor Circuit | |
| 6. Pressure switch circuit | DTC B1423/23 Pressure Sensor Circuit | |
| 7. Air mix damper control servo motor circuit (Driver side) | DTC B1446/46 Air Mix Damper Control Servo Motor Circuit (Driver Side) | |
| 7. Air mix damper control servo motor circuit (Passenger side) | DTC B1441/41 Air Mix Damper Control Servo Motor Circuit (Passenger Side) | |
| 8. Air mix damper position sensor circuit (Driver side) | DTC B1436/36 Air Mix Damper Position Sensor Circuit (Driver Side) | |
| 8. Air mix damper position sensor circuit (Passenger side) | DTC B1431/31 Air Mix Damper Position Sensor Circuit (Passenger Side) | |
| 9. Room temperature sensor circuit | DTC B1411/11 Room Temperature Sensor Circuit | |
| 10. Ambient temperature sensor circuit | DTC B1412/12 Ambient Temperature Sensor Circuit | |
| 11. A/C amplifier (A/C control) | TERMINALS OF ECU | |
| 12. Multiplex communication circuit | DTC B1499/99 Multiplex Communication Circuit | |
| Temperature Control: No warm air comes out | 1. Air mix damper control servo motor circuit (Driver side) | DTC B1446/46 Air Mix Damper Control Servo Motor Circuit (Driver Side) |
| 1. Air mix damper control servo motor circuit (Passenger side) | DTC B1441/41 Air Mix Damper Control Servo Motor Circuit (Passenger Side) | |
| 2. Air mix damper position sensor circuit (Driver side) | DTC B1436/36 Air Mix Damper Position Sensor Circuit (Driver Side) | |
| 2. Air mix damper position sensor circuit (Passenger side) | DTC B1431/31 Air Mix Damper Position Sensor Circuit (Passenger Side) | |
| 3. Room temperature sensor circuit | DTC B1411/11 Room Temperature Sensor Circuit | |
| 4. Ambient temperature sensor circuit | DTC B1412/12 Ambient Temperature Sensor Circuit | |
| 5. Evaporator temperature sensor circuit | DTC B1413/13 Evaporator Temperature Sensor Circuit | |
| 6. A/C amplifier (A/C control) | TERMINALS OF ECU | |
| 7. Multiplex communication circuit | DTC B1499/99 Multiplex Communication Circuit | |
| 8. Heater radiator | - | |
| Temperature Control: Output air is warmer or cooler than the set temperature or response is slow. | 1. Room temperature sensor circuit | DTC B1411/11 Room Temperature Sensor Circuit |
| 2. Ambient temperature sensor circuit | DTC B1412/12 Ambient Temperature Sensor Circuit | |
| 3. Solar sensor circuit (Driver side) | DTC B1424/24 Solar Sensor Circuit (Driver Side) | |
| 3. Solar sensor circuit (Passenger side) | DTC B1421/21 Solar Sensor Circuit (Passenger Side) | |
| 4. Air mix damper control servo motor circuit (Driver side) | DTC B1446/46 Air Mix Damper Control Servo Motor Circuit (Driver Side) | |
| 4. Air mix damper control servo motor circuit (Passenger side) | DTC B1441/41 Air Mix Damper Control Servo Motor Circuit (Passenger Side) | |
| 5. Air mix damper position sensor circuit (Driver side) | DTC B1436/36 Air Mix Damper Position Sensor Circuit (Driver Side) | |
| 5. Air mix damper position sensor circuit (Passenger side) | DTC B1431/31 Air Mix Damper Position Sensor Circuit (Passenger Side) | |
| 6. A/C amplifier (A/C control) | TERMINALS OF ECU | |
| 7. Multiplex communication circuit | DTC B1499/99 Multiplex Communication Circuit | |
| Temperature Control: No temperature control (only Max. cool or Max. warm) | 1. Air mix damper control servo motor circuit (Driver side) | DTC B1446/46 Air Mix Damper Control Servo Motor Circuit (Driver Side) |
| 1. Air mix damper control servo motor circuit (Passenger side) | DTC B1441/41 Air Mix Damper Control Servo Motor Circuit (Passenger Side) | |
| 2. Air mix damper position sensor circuit (Driver side) | DTC B1436/36 Air Mix Damper Position Sensor Circuit (Driver Side) | |
| 2. Air mix damper position sensor circuit (Passenger side) | DTC B1431/31 Air Mix Damper Position Sensor Circuit (Passenger Side) | |
| 3. A/C amplifier (A/C control) | TERMINALS OF ECU | |
| No air inlet control | 1. Air inlet damper control servo motor circuit | DTC B1442/42 Air Inlet Damper Control Servo Motor Circuit |
| 2. Air inlet damper position sensor circuit | DTC B1432/32 Air Inlet Damper Position Sensor Circuit | |
| 3. Emission gas sensor circuit | DTC B1418/18 Exhaust Gas Sensor Circuit | |
| 4. A/C amplifier (A/C control) | TERMINALS OF ECU | |
| No air outlet control | 1. Air outlet damper control servo motor circuit | DTC B1443/43 Air Outlet Damper Control Servo Motor Circuit |
| 2. Air outlet damper position sensor circuit | DTC B1433/33 Air Outlet Damper Position Sensor Circuit | |
| 3. Lap-jet damper control servo motor circuit | LAP-JET DAMPER CONTROL SERVO MOTOR CIRCUIT | |
| 4. A/C amplifier (A/C control) | TERMINALS OF ECU | |
| Engine idle up does not occur, or is continuous | 1. Compressor circuit | COMPRESSOR CIRCUIT |
| 2. Compressor lock sensor circuit | DTC B1422/22 Compressor Lock Sensor Circuit | |
| 3. A/C amplifier (A/C control) | TERMINALS OF ECU | |
| 4. Multiplex communication circuit | DTC B1499/99 Multiplex Communication Circuit | |
| Set temperature value displayed does not match up with operation of temperature control switch. | 1. A/C amplifier (A/C control) | TERMINALS OF ECU |
| Brightness does not changes when rheostat knob or lamp control switch is turned. | 1. Lighting system | PROBLEM SYMPTOMS TABLE |
| 2. Combination meter | PROBLEM SYMPTOMS TABLE | |
| 3. Wire harness or connector | - | |
| 4. A/C amplifier (A/C control) | TERMINALS OF ECU | |
| Unable to access the diagnosis mode. | 1. A/C amplifier (A/C control) | TERMINALS OF ECU |
| DTC(s) not recorded, (set mode is cleared when ignition switch is turned OFF) | 1. Back-up power source circuit | BACK-UP POWER SOURCE CIRCUIT |
| 2. A/C amplifier (A/C control) | TERMINALS OF ECU |