AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System) Power Heater Switch Circuit

DESCRIPTION

The power heater operates when the heater switch assembly is on and the following conditions are met:

• Ignition switch is ON.

• Air inlet control damper position is FRESH.

• Blower motor switch is in any position other than OFF.

• Air mix damper position is Max. HOT.

• Engine coolant temperature is below 65°C (149°F).

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. INSPECT HEATER SWITCH ASSEMBLY

   
   
   1. 

      Text in Illustration

      *1	Indicator Light

      Remove the heater switch assembly Click here.

   2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Switch Condition Specified Condition 4 - 1 Heater switch assembly on Below 1 Ω 4 - 1 Heater switch assembly off 10 kΩ or higher

   3. Apply battery voltage to the switch connector and check that the indicator light illuminates.

      OK
      Measurement Connection Specified Condition Battery positive (+) → Terminal 5 Indicator light illuminates Battery negative (-) → Terminal 8

   
   

   NG

   REPLACE HEATER SWITCH ASSEMBLY Click here

   OK

2. CHECK HARNESS AND CONNECTOR (HEATER SWITCH - AIR CONDITIONING AMPLIFIER AND BODY GROUND)

   
   

   1. Disconnect the P21 heater switch assembly connector.

   2. Disconnect the A43 air conditioning amplifier assembly connector.

   3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition P21-4 - A43-8 (HEAT) Always Below 1 Ω P21-5 - A43-5 (SWIN) P21-4 - Body ground Always 10 kΩ or higher P21-5 - Body ground P21-1 - Body ground Always Below 1 Ω P21-8 - Body ground

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

   PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here