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 Blower switch: Lo or more
Temperature set to HI
Combination switch off
Engine coolant temperature 69°C (156.2°F) or lower
Ambient temperature 3°C (37.4°F) or lower
Engine running

Tech Tips


  • When all operation conditions are met, 2 quick heater assemblies are operated.

  • The number of quick heater assemblies operated changes according to the engine coolant temperature.

WIRING DIAGRAM

A01FIYFE02

INSPECTION PROCEDURE

Note


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

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

  • Before disconnecting the cable form the negative (-) battery terminal or replacing the air conditioning amplifier assembly, record the last operation state of the air conditioning for each transmitter. After replacement, it is necessary to perform memory registration for each transmitter Click here.

PROCEDURE


  1. PERFORM ACTIVE TEST USING GTS (HEATER ACTIVE LEVEL)


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

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

    5. Check the operation by referring to the table below.

      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

    INSPECT PTC HEATER RELAY (PTC NO.1, PTC NO.2) Click here

    OK

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

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


    1. Remove the PTC heater relays Click here.

    2. Inspect the PTC heater relays Click here.


    NG

    REPLACE PTC HEATER RELAY (PTC NO.1 OR PTC NO.2) Click here

    OK

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


    1. Disconnect the N79 air conditioning amplifier assembly connector.

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

      Standard Voltage
      PTC NO.1 (for LHD)
      Tester Connection Condition Specified Condition
      5 - Body ground Always 11 to 14 V
      1 - Body ground Engine switch on (IG) 11 to 14 V
      1 - Body ground Engine switch off Below 1 V
      PTC NO.1 (for RHD)
      Tester Connection Condition Specified Condition
      5 - Body ground Always 11 to 14 V
      2 - Body ground Engine switch on (IG) 11 to 14 V
      2 - Body ground Engine switch off Below 1 V
      PTC NO.2
      Tester Connection Condition Specified Condition
      5 - Body ground Always 11 to 14 V
      1 - Body ground Engine switch on (IG) 11 to 14 V
      1 - Body ground Engine switch off Below 1 V

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

      Standard Resistance
      PTC NO.1 (for LHD)
      Tester Connection Condition Specified Condition
      2 - N79-8 (PTC1) Always Below 1 Ω
      2 - Body ground Always 10 kΩ or higher
      PTC NO.1 (for RHD)
      Tester Connection Condition Specified Condition
      1 - N79-8 (PTC1) Always Below 1 Ω
      1 - Body ground Always 10 kΩ or higher
      PTC NO.2
      Tester Connection Condition Specified Condition
      2 - N79-26 (PTC2) Always Below 1 Ω
      2 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Disconnect the N76 and N77 quick heater assembly connectors.

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

      Standard Resistance
      PTC NO.1
      Tester Connection Condition Specified Condition
      N76-2 (B) - 3 Always Below 1 Ω
      N76-1 (E) - Body ground Always Below 1 Ω
      N76-2 (B) - Body ground Always 10 kΩ or higher
      PTC NO.2
      Tester Connection Condition Specified Condition
      N77-2 (B) - 3 Always Below 1 Ω
      N77-1 (E) - Body ground Always Below 1 Ω
      N77-2 (B) - Body ground Always 10 kΩ or higher

    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.


    NG

    REPLACE QUICK HEATER ASSEMBLY Click here

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here