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

DESCRIPTION

The air conditioning amplifier assembly sends operation signals to the PTC heater relays when quick heater assembly operation conditions are met. Based on the signals from the air conditioning amplifier assembly, the PTC heater relays turn on, and power is supplied to the quick heater assembly installed in the air conditioning radiator assembly.

Quick Heater Assembly Operation Condition
Control ECU Condition
Air Conditioning Amplifier Assembly Start the engine
ECO mode switch: Off
Blower switch: LO or more
Temperature settings: MAX HOT
Light control switch: Off

  • Engine coolant temperature 65°C (149°F), or lower (3 PTC heater relays operating)

  • Engine coolant temperature 70°C (158°F), or lower (2 PTC heater relays operating)

  • Engine coolant temperature 75°C (167°F), or lower (A PTC heater relay operating)
Ambient temperature 10°C (50°F) or lower

WIRING DIAGRAM

B0025FGE04

CAUTION / NOTICE / HINT

Note


  • Inspect the fuses for circuits related to this system before performing the following procedure.

  • When the battery is disconnected or the air conditioning amplifier assembly is replaced, be sure to perform servo motor initialization.

    Click here

PROCEDURE


  1. INSPECT PTC HEATER RELAY (PTC HTR NO.1, PTC HTR NO.2, PTC HTR NO.3)


    1. Remove the PTC heater relays from the No. 5 instrument panel relay block.

    2. Inspect the PTC heater relays.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE PTC HEATER RELAY (PTC HTR NO.1, PTC HTR NO.2, PTC HTR NO.3)

    OK

  2. CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - BATTERY)


    1. Remove the PTC heater relays from the No. 5 instrument panel relay block.

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

      Standard Voltage
      PTC HTR NO.1
      Tester Connection Condition Specified Condition
      Relay terminal 5 - Body ground Always 11 to 14 V
      Relay terminal 1 - Body ground Ignition switch off Below 1 V
      Ignition switch ON 11 to 14 V
      PTC HTR NO.2
      Tester Connection Condition Specified Condition
      Relay terminal 5 - Body ground Always 11 to 14 V
      Relay terminal 1 - Body ground Ignition switch off Below 1 V
      Ignition switch ON 11 to 14 V
      PTC HTR NO.3
      Tester Connection Condition Specified Condition
      Relay terminal 5 - Body ground Always 11 to 14 V
      Relay terminal 2 - Body ground Ignition switch off Below 1 V
      Ignition switch ON 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - AIR CONDITIONING AMPLIFIER ASSEMBLY)


    1. Remove the PTC heater relays from the No. 5 instrument panel relay block.

    2. Disconnect the G33 air conditioning amplifier assembly connector.

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

      Standard Resistance
      PTC HTR NO.1
      Tester Connection Condition Specified Condition
      Relay terminal 2 - G33-39 (PTC1) Always Below 1 Ω
      Relay terminal 2 or G33-39 (PTC1)- Body ground Always 10 kΩ or higher
      PTC HTR NO.2
      Tester Connection Condition Specified Condition
      Relay terminal 2 - G33-40 (PTC2) Always Below 1 Ω
      Relay terminal 2 or G33-40 (PTC2) - Body ground Always 10 kΩ or higher
      PTC HTR NO.3
      Tester Connection Condition Specified Condition
      Relay terminal 1 - G33-3 (PTC3) Always Below 1 Ω
      Relay terminal 1 or G33-3 (PTC3) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK HARNESS AND CONNECTOR (QUICK HEATER ASSEMBLY - PTC HEATER RELAY AND BODY GROUND)


    1. Remove the PTC heater relays from the No. 5 instrument panel relay block.

    2. Disconnect the G78 and G79 quick heater assembly connectors.

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

      Standard Resistance
      PTC HTR NO.1
      Tester Connection Condition Specified Condition
      G79-3 (B) - Relay terminal 3 Always Below 1 Ω
      G78-1 (E) - Body ground Always Below 1 Ω
      G79-2 (E) - Body ground Always Below 1 Ω
      G79-3 (B) or relay terminal 3 - Body ground Always 10 kΩ or higher
      PTC HTR NO.2
      Tester Connection Condition Specified Condition
      G79-1 (B) - Relay terminal 3 Always Below 1 Ω
      G79-2 (E) - Body ground Always Below 1 Ω
      G79-1 (B) or relay terminal 3 - Body ground Always 10 kΩ or higher
      PTC HTR NO.3
      Tester Connection Condition Specified Condition
      G78-2 (B) - Relay terminal 3 Always Below 1 Ω
      G78-1 (E) - Body ground Always Below 1 Ω
      G78-2 (B) or relay terminal 3 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. INSPECT QUICK HEATER ASSEMBLY


    1. Remove the quick heater assembly.

      Click here

    2. Inspect the quick heater assembly.

      Click here

      Result
      Proceed to
      OK
      NG

    OK

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

    NG

    REPLACE QUICK HEATER ASSEMBLY Click here