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

DESCRIPTION

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

Symptom Factor
Heating performance is poor when it is cold.

  • Quick heater assembly malfunction

  • Air conditioning amplifier assembly malfunction

  • PTC HTR relay malfunction

  • Harness or connector

WIRING DIAGRAM

B00863JE06

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


  1. INSPECT PTC HTR RELAY


    1. Inspect the PTC HTR relays.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE PTC HTR RELAY

    OK

  2. CHECK HARNESS AND CONNECTOR (POWER SOURCE - PTC HTR RELAY)


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

      Standard Voltage
      PTC HTR NO. 1
      Tester Connection Condition Specified Condition
      3 (PTC HTR NO. 1 relay) - Body ground Always 11 to 14 V
      2 (PTC HTR NO. 1 relay) - Body ground Ignition switch off Below 1 V
      2 (PTC HTR NO. 1 relay) - Body ground Ignition switch ON 11 to 14 V
      PTC HTR NO. 2
      Tester Connection Condition Specified Condition
      3 (PTC HTR NO. 2 relay) - Body ground Always 11 to 14 V
      2 (PTC HTR NO. 2 relay) - Body ground Ignition switch off Below 1 V
      2 (PTC HTR NO. 2 relay) - Body ground 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 HTR RELAY - AIR CONDITIONING AMPLIFIER ASSEMBLY)


    1. Disconnect the K54 and K55 air conditioning amplifier assembly connectors.

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

      Standard Resistance
      PTC HTR NO. 1
      Tester Connection Condition Specified Condition
      1 (PTC HTR NO. 1 relay) - K54-18 (PTC1) Always Below 1 Ω
      1 (PTC HTR NO. 1 relay) or K54-18 (PTC1) - Other terminals and body ground Always 10 kΩ or higher
      PTC HTR NO. 2
      Tester Connection Condition Specified Condition
      1 (PTC HTR NO. 2 relay) - K55-10 (PTC2) Always Below 1 Ω
      1 (PTC HTR NO. 2 relay) or K55-10 (PTC2) - Other terminals and 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 (PTC HTR RELAY - QUICK HEATER ASSEMBLY AND BODY GROUND)


    1. Disconnect the L1 and L2 quick heater assembly connectors.

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

      Standard Resistance
      PTC HTR NO. 1
      Tester Connection Condition Specified Condition
      5 (PTC HTR NO. 1 relay) - L1-2 (B) Always Below 1 Ω
      5 (PTC HTR NO. 1 relay) - L2-1 (B) Always Below 1 Ω
      5 (PTC HTR NO. 1 relay) or L1-2 (B) - Other terminals and body ground Always 10 kΩ or higher
      5 (PTC HTR NO. 1 relay) or L2-1 (B) - Other terminals and body ground Always 10 kΩ or higher
      PTC HTR NO. 2
      Tester Connection Condition Specified Condition
      5 (PTC HTR NO. 2 relay) - L2-3 (B) Always Below 1 Ω
      5 (PTC HTR NO. 2 relay) or L2-3 (B) - Other terminals and 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

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

    REPLACE QUICK HEATER ASSEMBLY Click here