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Problem Symptoms Table

WARNING: This page is about a different car, the 2003 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
PROBLEM SYMPTOMS REFERENCE

Symptom Suspect Area See page
Whole functions of the A/C system does not operate
  1. A/C amplifier
  2. ACC power source circuit
  1. INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)
  2. See ACC POWER SOURCE CIRCUIT 
Air Flow Control: No blower operation
  1. ACC power source circuit
  2. Heater main relay circuit
  3. Blower motor circuit
  4. A/C amplifier
  1. See ACC POWER SOURCE CIRCUIT 
  2. See HEATER MAIN RELAY CIRCUIT 
  3. See BLOWER MOTOR CIRCUIT 
  4. INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)
Air Flow Control: No blower control
  1. Heater main relay circuit
  2. Blower motor circuit
  3. A/C amplifier
  4. Solar sensor circuit
  1. See HEATER MAIN RELAY CIRCUIT 
  2. See BLOWER MOTOR CIRCUIT 
  3. INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)
  4. See DTC B1421 SOLAR SENSOR CIRCUIT 
Air Flow Control: Insufficient air flow Blower motor circuit See BLOWER MOTOR CIRCUIT 
Temperature Control: No cool air comes out
  1. Refrigerant volume
  2. Drive belt tension
  3. Refrigeration system inspection with manifold gauge set
  4. Compressor circuit
  5. Pressure switch circuit
  6. Air mix damper position sensor circuit
  7. Air mix damper control servomotor circuit
  8. Room temp. sensor circuit
  9. Ambient temp. sensor circuit
  10. A/C amplifier
  1. See REPLACEMENT
  2. See DRIVE BELT
  3. See ON-VEHICLE INSPECTION
  4. See COMPRESSOR CIRCUIT 
  5. See DTC B1423 PRESSURE SWITCH CIRCUIT 
  6. See DTC B1431 AIR MIX DAMPER POSITION SENSOR CIRCUIT 
  7. See DTC B1441 AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT 
  8. See DTC B1411 ROOM TEMPERATURE SENSOR CIRCUIT 
  9. See DTC B1412 AMBIENT TEMPERATURE SENSOR CIRCUIT 
  10. INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)

 
Temperature Control: No warm air comes out
  1. Air mix damper position sensor circuit
  2. Air mix damper control servomotor circuit
  3. Room temp. sensor circuit
  4. Ambient temp. sensor circuit
  5. Evaporator temp. sensor circuit
  6. A/C amplifier
  1. See DTC B1431 AIR MIX DAMPER POSITION SENSOR CIRCUIT 
  2. See DTC B1441 AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT 
  3. See DTC B1411 ROOM TEMPERATURE SENSOR CIRCUIT 
  4. See DTC B1412 AMBIENT TEMPERATURE SENSOR CIRCUIT 
  5. See DTC B1413 EVAPORATOR TEMPERATURE SENSOR CIRCUIT 
  6. INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)
Temperature Control: Output air is warmer or cooler than the set temperature or response is slow
  1. Refrigerant volume
  2. Drive belt tension
  3. Refrigeration system inspection with manifold gauge set
  4. Cooling fan system
  5. Solar sensor circuit
  6. Room temp. sensor circuit
  7. Ambient temp. sensor circuit
  8. Evaporator temp. sensor circuit
  9. Air mix damper position sensor circuit
  10. Air mix damper control servomotor circuit
  11. Air inlet damper position sensor circuit
  12. Air inlet damper control servomotor circuit
  13. Condenser
  14. Evaporator
  15. Heater radiator
  16. Expansion valve
  17. A/C amplifier
  1. See REPLACEMENT
  2. See DRIVE BELT
  3. See ON-VEHICLE INSPECTION
  4. See ELECTRIC COOLING FANS
  5. See DTC B1421 SOLAR SENSOR CIRCUIT 
  6. See DTC B1411 ROOM TEMPERATURE SENSOR CIRCUIT 
  7. See DTC B1412 AMBIENT TEMPERATURE SENSOR CIRCUIT 
  8. See DTC B1413 EVAPORATOR TEMPERATURE SENSOR CIRCUIT 
  9. See DTC B1431 AIR MIX DAMPER POSITION SENSOR CIRCUIT 
  10. See DTC B1441 AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT 
  11. See DTC B1432 AIR INLET DAMPER POSITION SENSOR CIRCUIT 
  12. See DTC B1442 AIR INLET DAMPER CONTROL SERVOMOTOR CIRCUIT 
  13. See CONDENSER
  14. See INSPECTION
  15. See INSPECTION
  16. See EXPANSION VALVE
  17. INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)
Temperature Control: No temperature control (only Max. cool or Max. warm)
  1. Room temp. sensor circuit
  2. Ambient temp. sensor circuit
  3. Air mix damper position sensor circuit
  4. Air mix damper control servomotor circuit
  5. A/C amplifier
  1. See DTC B1411 ROOM TEMPERATURE SENSOR CIRCUIT 
  2. See DTC B1412 AMBIENT TEMPERATURE SENSOR CIRCUIT 
  3. See DTC B1431 AIR MIX DAMPER POSITION SENSOR CIRCUIT 
  4. See DTC B1441 AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT 
  5. INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)
No air inlet control
  1. Air inlet damper position sensor circuit
  2. Air inlet damper control servomotor circuit
  3. A/C amplifier
  1. See DTC B1432 AIR INLET DAMPER POSITION SENSOR CIRCUIT 
  2. See DTC B1442 AIR INLET DAMPER CONTROL SERVOMOTOR CIRCUIT 
  3. INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)
No air flow mode
  1. Air outlet damper position sensor circuit
  2. Air outlet damper control servomotor circuit
  3. A/C amplifier
  1. See DTC B1433 AIR OUTLET DAMPER POSITION SENSOR CIRCUIT 
  2. See DTC B1443 AIR OUTLET DAMPER CONTROL SERVOMOTOR CIRCUIT 
  3. INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)
Engine idle up does not occur, or is continuous
  1. Compressor circuit
  2. A/C amplifier
  1. See COMPRESSOR CIRCUIT 
  2. INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)
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