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(TE, SG)
1. Remove A/C amplifier with connectors still connected.
2. Turn ignition switch ON.
3. Measure voltage between terminals TE and SG of A/C amplifier connector at each temperature.
  Voltage
  
  at 0°C (32°F): 2.0 to 2.4 V
  
  at 15°C (59°F): 1.4 to 1.8 V
  
  Fig 1: Measuring Voltage Between Terminals TE And SG Of A/C Amplifier Connector At Each Temperature
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 2: Inspection 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 COOLER THERMISTOR NO.1
1. Remove cooler thermistor No. 1.
2. Check resistance between terminals 1 and 2 of cooler thermistor No. 1 at each temperature, as shown in the chart.
  Standard
  
  Fig 3: Identifying Tester Connection Specified Condition Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 4: Checking Resistance Between Terminals 1 And 2 Of Cooler Thermistor
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NOTE: Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.

HINT: As the temperature increases, the resistance decreases (see the chart below).

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

NG: REPLACE COOLER THERMISTOR NO.1

OK: Go to next step.
CHECK HARNESS AND CONNECTOR(BETWEEN COOLER THERMISTOR NO.1 AND HEATER CONTROL HOUSING SUB-ASSY)
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: CHECK AND REPLACE HEATER CONTROL HOUSING SUB-ASSY