Heater Unit: Inspection

Inspect Heater Radiator Fins For Blockage
If the fins are clogged, clean them with compressed air.
Inspect Air Mix Servomotor Circuit. See DTC 41 AIR MIX CONTROL SERVOMOTOR CIRCUIT .
Inspect Air Mix Damper Position Circuit. See DTC 31, 41 AIR MIX DAMPER POSITION SENSOR CIRCUIT .
Manual A/C model:
Inspect Air Mix Servomotor
1. Inspect servomotor operation.
  1. Connect the positive (+) lead from the battery to terminal 4 and negative (-) lead to terminal 5, then check that the arm turns to "COOL" side smoothly.
    
    Fig 1: Inspecting Air Mix Servomotor Operation (COOL)
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. Connect the positive (+) lead from the battery to terminal 5 and negative (-) lead to terminal 4, then check that the arm turns to "WARM" side smoothly.
    
    Fig 2: Inspecting Air Mix Servomotor Operation (WARM)
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  If operations are not as specified, replace the air mix servomotor.
2. Inspect position sensor resistance.
  
  Fig 3: Inspecting Position Sensor Resistance
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Measure resistance between terminals at servomotor arm each position as shown in Fig 4.
  
  Fig 4: Displaying Connection & Condition Resistance
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  If resistance is not as specified, replace the servomotor.