Inspection Procedure

WARNING: This page is about a different car, the 2004 Lexus ES 330. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT HEATER CONTROL HOUSING SUB-ASSY(TPD, SG-3)
1. Remove the A/C amplifier with connectors still connected.
2. Turn ignition switch ON.
3. Change the driver side set temperature to activate the air mix damper and measure the voltage between terminals TPD and SG-3 of A/C amplifier.
  Voltage:
  
  MAX. COLD: 3.5 to 4.5 V
  
  MAX. HOT: 0.5 to 1.8 V
HINT: As the set temperature increases, the voltage decreases gradually without interruption.

Fig 1: Measuring Voltage Between Terminals TPD And SG-3 Of A/C Amplifier
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: Inspection Procedure Chart
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE (SEE PROBLEM SYMPTOMS TABLE )

C: CHECK AND REPLACE HEATER CONTROL HOUSING SUB-ASSY

A: Go to next step.
INSPECT AIRMIX DAMPER SERVO SUB-ASSY
1. Remove the air mix damper servo sub-assy.
2. Measure resistance between terminals 1 and 2 of air mix damper servo sub-assy connector.
  Resistance: 4.2 to 7.8 kΩ
3. While operating air mix damper servo sub-assy as shown in the procedure on PRE-CHECK , measure resistance between terminals 1 and 3 of air mix damper servo sub-assy.
  Resistance:
  
  MAX. COOL: 3.4 to 6.2 kΩ
  
  MAX. HOT: 0.8 to 1.6 kΩ
HINT: As the air mix damper servo sub-assy moves from COLD side to HOT side, the resistance decreases gradually without interruption.

Fig 3: Measuring Resistance Between Terminals 1 And 2 Of Air Mix Damper Servo Sub-Assy Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 4: Identifying Position Of Air Mix Damper Servo
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 5: Identifying Graphic Of Resistance
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: REPLACE AIRMIX DAMPER SERVO SUB-ASSY

OK: Go to next step.
CHECK HARNESS AND CONNECTOR(BETWEEN AIR MIX DAMPER POSITION SENSOR AND HEATER CONTROL HOUSING SUB-ASSY)
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: CHECK AND REPLACE HEATER CONTROL HOUSING SUB-ASSY