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 (PTC Heater) Operation Condition
Control ECU Condition
Air Conditioning Amplifier Assembly Engine running
Blower switch: On
Temperature settings: MAX HOT
Light control switch off

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

  • Engine coolant temperature 75°C (167°F) or lower (1 PTC heater relay operating)
Ambient temperature 10°C (50°F) or lower

WIRING DIAGRAM

B000K74E03

INSPECTION PROCEDURE

Note

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

PROCEDURE


  1. PERFORM ACTIVE TEST USING INTELLIGENT TESTER


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the intelligent tester on.

    4. Enter the following menus: Body / Air Conditioner / Active Test.

    5. Perform the Active Test according to the display on the intelligent tester.

      Air Conditioner
      Tester Display Test Part Control Range Diagnostic Note
      Heater Active Level Quick heater assembly Min.: 0, Max.: 2 -
      OK
      Heater Active Level changes normally.

    NG

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

    OK

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


    1. B000IVGE02
      Text in illustration
      *a

      Component without harness connected

      (PTC Heater Relay)

      Remove the PTC HTR NO. 1 relay and PTC HTR NO. 2 relay.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3 - 5 Battery voltage not applied between terminals 1 and 2 10 kΩ or higher
      3 - 5 Battery voltage applied between terminals 1 and 2 Below 1 Ω

    NG

    REPLACE PTC HEATER RELAY

    OK

  3. CHECK HARNESS AND CONNECTOR (PTC HTR NO. 1 RELAY, PTC HTR NO. 2 RELAY - POWER SOURCE)


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

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK HARNESS AND CONNECTOR (PTC HTR NO. 1 RELAY, PTC HTR NO. 2 RELAY - AIR CONDITIONING AMPLIFIER ASSEMBLY)


    1. Disconnect the I77 air conditioning amplifier assembly connector.

    2. 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 1 - I77-15 (PTC1) Always Below 1 Ω
      Relay terminal 1 - Body ground Always 10 kΩ or higher
      Standard Resistance
      PTC HTR NO. 2
      Tester Connection Condition Specified Condition
      Relay terminal 1 - I77-16 (PTC2) Always Below 1 Ω
      Relay terminal 1 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK HARNESS AND CONNECTOR (PTC HTR NO. 1 RELAY, PTC HTR NO. 2 RELAY - QUICK HEATER ASSEMBLY AND BODY GROUND)


    1. Disconnect the I202 quick heater assembly connector.

    2. 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 5 - I202-1 (B) Always Below 1 Ω
      I202-1 (B) - Body ground Always 10 kΩ or higher
      Standard Resistance
      PTC HTR NO. 2
      Tester Connection Condition Specified Condition
      Relay terminal 5 - I202-2 (B) Always Below 1 Ω
      I202-2 (B) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. INSPECT QUICK HEATER ASSEMBLY


    1. Remove the quick heater assembly Click here.

    2. B000L65E14
      Text in Illustration
      *a

      Component without harness connected

      (Quick Heater Assembly)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I202-1 (B) - a1-1 (E) Always Below 1 Ω
      I202-2 (B) - a1-1 (E) Always Below 1 Ω

    NG

    REPLACE QUICK HEATER ASSEMBLY Click here

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here