AIR CONDITIONING SYSTEM PTC Heater Circuit

DESCRIPTION

PTC heater relays are closed in accordance with signals from the air conditioning amplifier and power is supplied to the PTC heater installed on the radiator heater unit.

WIRING DIAGRAM

A001FC5E02

PROCEDURE


  1. INSPECT FUSE (PTC HTR1, PTC HTR2, PTC HTR3, PTC HTR)


    1. Remove the PTC HTR1 and PTC HTR3 fuses, and PTC HTR and PTC HTR2 H-fuses from the No. 1 engine room relay block.

    2. Measure the resistance of the fuses.

      Standard resistance
      Tester Connection Condition Specified Condition
      PTC HTR1 fuse Always Below 1 Ω
      PTC HTR2 H-fuse Always Below 1 Ω
      PTC HTR3 fuse Always Below 1 Ω
      PTC HTR H-fuse Always Below 1 Ω

    NG

    REPLACE FUSE

    OK

  2. CHECK AIR CONDITIONING AMPLIFIER

    A001A1HE01

    1. Remove the air conditioning amplifier with its connectors still connected Click here.

    2. Turn the engine switch on (IG).

    3. When the PTC heater operating conditions are met (engine at idling speed or faster, ambient temperature is 10°C (50°F) or less, engine coolant temperature is 65°C (149°F) or less, set temperature switch is set to MAX HOT), turn the blower switch to the LO setting.

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

      Standard voltage
      Tester Connection Switch Condition Specified Condition
      L76-27 (PTC1) - Body ground

      Engine switch on (IG)

      Blower Switch LO

      		 11 to 14 V
      L76-26 (PTC2) - Body ground

      Engine switch on (IG)

      Blower Switch LO

      		 11 to 14 V
      L76-35 (PTC3) - Body ground

      Engine switch on (IG)

      Blower Switch LO

      		 11 to 14 V

    OK

    REPLACE AIR CONDITIONING AMPLIFER Click here

    NG

  3. INSPECT PTC HEATER RELAY (PTC HTR1, PTC HTR2, PTC HTR3)

    A001FFFE02
    *a No. 2 PTC Heater Relay (PTC HTR2)
    *b No. 1 and No. 3 PTC Heater Relays (PTC HTR1, PTC HTR3)

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

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

      Standard resistance
      Tester Connection Condition Specified Condition
      3 - 5 When battery voltage is not applied between terminals 1 and 2 10 kΩ or higher
      When battery voltage is applied to terminals 1 and 2 Below 1 Ω

    NG

    REPLACE PTC HEATER RELAY

    OK

  4. CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - PTC HEATER)

    A001E35E01

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

    2. Disconnect the L40 PTC heater connector.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      PTC HTR1 terminal 3 - L40-1 (B) Always Below 1 Ω
      PTC HTR2 terminal 5 - L40-2 (B) Always Below 1 Ω
      PTC HTR3 terminal 3 - L40-3 (B) Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK PTC HEATER

    A001BYEE01
    *1 Component without harness connected: (PTC Heater)

    1. Disconnect the L40 and L41 PTC heater connectors.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      L40-1 (B) - L41-1 (E) Always Below 1 Ω
      L40-2 (B) - L41-1 (E) Always Below 1 Ω
      L40-1 (B) - L41-2 (E) Always Below 1 Ω
      L40-3 (B) - L41-2 (E) Always Below 1 Ω

    NG

    REPLACE PTC HEATER Click here

    OK

  6. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - BODY GROUND)

    A001A1HE01

    1. Remove the air conditioning amplifier with its connectors still connected Click here.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      L76-27 (PTC1) - Body ground Always Below 1 Ω
      L76-26 (PTC2) - Body ground Always Below 1 Ω
      L76-35 (PTC3) - Body ground Always Below 1 Ω

    OK

    REPLACE AIR CONDITIONING AMPLIFER Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR