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.

Control ECU Condition
Air Conditioning Amplifier Assembly Start the engine
Integration control and panel assembly (ECO mode switch) off
Blower switch: LO or more
Temperature settings: MAX HOT

  • 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

B001AJ6E21

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


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


    1. Remove the PTC heater relay from the No. 1 engine room relay block.

    2. Inspect the PTC heater relay Click here.


    NG

    REPLACE PTC HEATER RELAY

    OK

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


    1. Remove the PTC heater relays from the No. 1 engine room 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 block PTC HTR NO.1 relay terminal 2 - Body ground Engine switch off Below 1 V
      Relay block PTC HTR NO.1 relay terminal 2 - Body ground Engine switch on (IG) 11 to 14 V
      Relay block PTC HTR NO.1 relay terminal 5 - Body ground Always 11 to 14 V
      PTC HTR NO.2
      Tester Connection Condition Specified Condition
      Relay block PTC HTR NO.2 relay terminal 2 - Body ground Engine switch off Below 1 V
      Relay block PTC HTR NO.2 relay terminal 2 - Body ground Engine switch on (IG) 11 to 14 V
      Relay block PTC HTR NO.2 relay terminal 5 - Body ground Always 11 to 14 V
      PTC HTR NO.3
      Tester Connection Condition Specified Condition
      Relay block PTC HTR NO.3 relay terminal 2 - Body ground Engine switch off Below 1 V
      Relay block PTC HTR NO.3 relay terminal 2 - Body ground Engine switch on (IG) 11 to 14 V
      Relay block PTC HTR NO.3 relay terminal 5 - Body ground Always 11 to 14 V

    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. 1 engine room relay block.

    2. Disconnect the E36 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 block PTC HTR NO.1 relay terminal 1 - E36-8 (PTC1) Always Below 1 Ω
      Relay block PTC HTR NO.1 relay terminal 1 or E36-8 (PTC1) - Body ground Always 10 kΩ or higher
      PTC HTR NO.2
      Tester Connection Condition Specified Condition
      Relay block PTC HTR NO.2 relay terminal 1 - E36-26 (PTC2) Always Below 1 Ω
      Relay block PTC HTR NO.2 relay terminal 1 or E36-26 (PTC2) - Body ground Always 10 kΩ or higher
      PTC HTR NO.3
      Tester Connection Condition Specified Condition
      Relay block PTC HTR NO.3 relay terminal 1 - E36-24 (PTC3) Always Below 1 Ω
      Relay block PTC HTR NO.3 relay terminal 1 or E36-24 (PTC3) - 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. Remove the PTC heater relays from the No. 1 engine room relay block.

    2. Disconnect the E33 and E34 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
      E33-2 (B) - Relay block PTC HTR NO.1 relay terminal 3 Always Below 1 Ω
      E34-1 (E) - Body ground Always Below 1 Ω
      E34-2 (E) - Body ground Always Below 1 Ω
      E33-2 (B) or Relay block PTC HTR NO.1 relay terminal 3 - Body ground Always 10 kΩ or higher
      PTC HTR NO.2
      Tester Connection Condition Specified Condition
      E33-1 (B) - Relay block PTC HTR NO.2 relay terminal 3 Always Below 1 Ω
      E34-1 (E) - Body ground Always Below 1 Ω
      E33-1 (B) or Relay block PTC HTR NO.2 relay terminal 3 - Body ground Always 10 kΩ or higher
      PTC HTR NO.3
      Tester Connection Condition Specified Condition
      E33-3 (B) - Relay block PTC HTR NO.3 relay terminal 3 Always Below 1 Ω
      E34-2 (E) - Body ground Always Below 1 Ω
      E33-3 (B) or Relay block PTC HTR NO.3 relay terminal 3 - 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.


    OK

    PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    NG

    REPLACE QUICK HEATER ASSEMBLY Click here