PTC Heater Circuit

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

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. INSPECT FUSE (PTC NO. 1, PTC NO. 2, PTC NO. 3)

(a) Remove the PTC NO. 1, PTC NO. 2 and PTC NO. 3 fuses from the engine room No. 2 relay block.

(b) Measure the resistance of the fuses.

Standard resistance:





NG -- REPLACE FUSE
OK -- Continue to next step.

2. INSPECT PTC HEATER RELAY

(a) Remove the No. 1, No. 2 and No. 3 PTC heater relays from the engine room No. 2 relay block.





(b) Measure the resistance of the relays.

Standard resistance:





NG -- REPLACE PTC HEATER RELAY
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - BODY GROUND)

(a) Remove the No. 1, No. 2 and No. 3 PTC heater relays from the engine room No. 2 relay block.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

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

(a) Remove the No. 1, No. 2 and No. 3 PTC heater relays from the engine room No. 2 relay block.





(b) Turn the ignition switch on (IG).

(c) 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.

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

Standard voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

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

(a) Remove the No. 1, No. 2 and No. 3 PTC heater relays from the engine room No. 2 relay block.





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

Standard voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

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

(a) Remove the No. 1, No. 2 and No. 3 PTC heater relays from the engine room No. 2 relay block.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

7. CHECK AIR CONDITIONING AMPLIFIER

(a) Remove the air conditioning amplifier Removal with its connectors still connected.





(b) Turn the ignition switch on (IG).

(c) 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.

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

Standard voltage:





NG -- REPLACE AIR CONDITIONING AMPLIFIER
OK -- Continue to next step.

8. REPLACE PTC HEATER

(a) Replace the PTC heater Disassembly.

NEXT -- Continue to next step.

9. CHECK PTC HEATER (OPERATION)

(a) Operate the PTC heater to check that it functions properly.

OK:

PTC heater function operates normally.

NG -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Air Conditioning System (For Automatic Air Conditioning System)

OK -- END (PTC HEATER IS DEFECTIVE)