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

DESCRIPTION

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

INSPECTION PROCEDURE

PROCEDURE

1. Click here

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

   
   
   1. 

      Remove the PTC NO. 1, PTC NO. 2 and PTC NO. 3 relays from the engine room No. 2 relay block.

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

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

   
   
   • OKClick here
   • NGClick here
2. Click here

   CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY

   
   
   1. 

      Remove the air conditioning amplifier assembly with its connectors still connected (Click here).

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

      Standard Voltage

      Tester Connection Condition Specified Condition G25-3 (PTC1) - Body ground Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 79°C (174°F) or less Headlight dimmer switch off Blower switch off Below 1 V* G25-22 (PTC2) - Body ground Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 76°C (169°F) or less Headlight dimmer switch off Blower switch off G25-4 (PTC3) - Body ground Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 73°C (163°F) or less Headlight dimmer switch off Blower switch off G25-3 (PTC1) - Body ground Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 79°C (174°F) or less Headlight dimmer switch off Blower switch on 11 to 14 V* G25-22 (PTC2) - Body ground Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 76°C (169°F) or less Headlight dimmer switch off Blower switch on G25-4 (PTC3) - Body ground Engine running (1250 rpm or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 73°C (163°F) or less Headlight dimmer switch off Blower switch on

      Table 1. Text in Illustration

      *a	Component with harness connected (Air Conditioning Amplifier Assembly)

      Tip:

      *: After the measurement conditions are met, wait 30 seconds before performing measurements.

   
   
   • OKClick here
   • NGClick here
3. Click here

   CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 2 RELAY BLOCK - AIR CONDITIONING AMPLIFIER)

   
   

   1. Remove the PTC heater relays from the engine room No. 2 relay block.

   2. Disconnect the G25 amplifier connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition PTC NO. 1 relay terminal 1 - G25-3 (PTC1) Always Below 1 Ω PTC NO. 2 relay terminal 1 - G25-22 (PTC2) PTC NO. 3 relay terminal 1 - G25-4 (PTC3) PTC NO. 1 relay terminal 1 - Body ground Always 10 kΩ or higher PTC NO. 2 relay terminal 1 - Body ground PTC NO. 3 relay terminal 1 - Body ground

   
   
   • OKClick here
   • NGClick here
4. Click here

   CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 2 RELAY BLOCK - QUICK HEATER)

   
   

   1. Remove the PTC heater relays from the engine room No. 2 relay block.

   2. Disconnect the G28 heater connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition PTC NO. 1 relay terminal 3 - G28-2 (B) Always Below 1 Ω PTC NO. 2 relay terminal 3 - G28-3 (B) PTC NO. 3 relay terminal 3 - G28-1 (B) PTC NO. 1 relay terminal 3 - Body ground Always 10 kΩ or higher PTC NO. 2 relay terminal 3 - Body ground PTC NO. 3 relay terminal 3 - Body ground

   
   
   • OKClick here
   • NGClick here
5. Click here

   CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 2 RELAY BLOCK - BATTERY AND BODY GROUND)

   
   
   1. 

      Remove the PTC heater relays from the engine room No. 2 relay block.

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

      Standard Voltage
      Tester Connection Condition Specified Condition PTC NO. 1 relay terminal 5 - Body ground Always 11 to 14 V PTC NO. 2 relay terminal 5 - Body ground PTC NO. 3 relay terminal 5 - Body ground

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

      Standard Resistance
      Tester Connection Condition Specified Condition PTC NO. 1 relay terminal 2 - Body ground Always Below 1 Ω PTC NO. 2 relay terminal 2 - Body ground PTC NO. 3 relay terminal 2 - Body ground

      Table 2. Text in Illustration

      *1	PTC NO. 1 Relay
      *2	PTC NO. 2 Relay
      *3	PTC NO. 3 Relay
      *a	Component without relay installed (Engine Room No. 2 Relay Block)

   
   
   • OKClick here
   • NGClick here
6. Click here

   INSPECT QUICK HEATER ASSEMBLY

   
   
   1. 

      Remove the quick heater assembly (Click here).

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

      Standard Resistance
      Tester Connection Condition Specified Condition 1 (B) - 1 (E) Always Below 1 kΩ 2 (B) - 1 (E) 2 (B) - 2 (E) 3 (B) - 2 (E)

   
   
   • OKClick here
   • NGClick here
7. Click here

   CHECK HARNESS AND CONNECTOR (QUICK HEATER - BODY GROUND)

   
   
   1. 

      Disconnect the G29 heater connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition G29-1 (E) - Body ground Always Below 1 Ω G29-2 (E) - Body ground

      Table 3. Text in Illustration

      *a	Front view of wire harness connector (to Quick Heater Assembly)

   
   
   • OKClick here
   • NGClick here
8. Click here

   REPLACE PTC HEATER RELAY (PTC NO. 1, PTC NO. 2, PTC NO. 3)

9. Click here

   REPAIR OR REPLACE HARNESS OR CONNECTOR

10. Click here

    REPLACE QUICK HEATER ASSEMBLYClick here

11. Click here

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLEClick here