Rear A/C Control Assembly: Inspection

WARNING: This page is about a different car, the 2003 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.

REMOVE REAR HEATER CONTROL ASSEMBLY
Using a screwdriver, release the 4 claws and pull out the rear heater control assembly, then disconnect the connector.

Fig 1: Releasing 4 Claws And Pulling Out Rear Heater Control Assembly
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
INSPECT ILLUMINATION OPERATION
Connect the positive (+) lead to terminal 2 and negative (-) lead to terminal 21 then check that the indicators come on.

If operation is not as specified, replace the rear A/C control assembly.

Fig 2: Inspecting Illumination Operation
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INSPECT INDICATOR OPERATION
1. Connect the positive (+) lead all the other terminals to terminal 1 and negative (-) lead to, then check that the indicator comes on, as shown in the chart.
  
  Fig 3: Inspecting Indicator Operation
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  If operation is not as specified, replace the rear A/C control assembly.
  
  Fig 4: Switch And Tester Connection Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Connect the positive (+) lead from the battery to terminal 2, then check whether the indicators dim.
  If operation is not as specified, replace the rear A/C control assembly.
  
  Fig 5: Inspecting Indicator Operation
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
INSPECT SWITCH CONTINUITY
Check the continuity between terminals while switch is pressed as shown in the chart.

Fig 6: Identifying Switch Connector Terminals
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If continuity is not as specified, replace the rear A/C control assembly.

Fig 7: Switch Continuity Condition Chart
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INSPECT VARIABLE RESISTOR OPERATION
1. Measure resistance between terminal 10 and 12.
  Standard resistance: 3.0 kΩ
2. Gradually move the temperature control lever from "COOL" side to "WARM" side, then check that the resistance between terminal 11 and 12 increase to 3.0kΩ.
  If operation is not as specified, replace the rear A/C control assembly.
  
  Fig 8: Inspecting Variable Resistor Operation
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
INSTALL HEATER CONTROL ASSEMBLY