PTC Heater Circuit

AIR CONDITIONING: 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 installed on the radiator heater unit.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

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

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

(b) Measure the resistance of the fuses.

Standard resistance:





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

2. CHECK AIR CONDITIONING AMPLIFIER





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

(b) Turn the engine 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 Removal
OK -- Continue to next step.

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





(a) Remove the PTC heater relays from the No. 5 relay block.

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

Standard resistance:





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

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





(a) Remove the PTC heater relays from the No. 5 relay block.

(b) Disconnect the L40 PTC heater connector.

(c) 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.

5. CHECK PTC HEATER





(a) Disconnect the L40 and L41 PTC heater connectors.

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

Standard resistance:





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

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





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

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE AIR CONDITIONING AMPLIFIER Removal