PTC Heater Circuit

HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM: PTC Heater Circuit
- PTC Heater Circuit

DESCRIPTION

The PTC heater assembly is installed in the radiator in the heater unit and operates when engine coolant temperature is low and normal heater effectiveness is insufficient.

The A/C control assembly switches the circuit in the PTC relay and operates the PTC heater assembly when the operating conditions (cooling water temperature is below 65°C (149°F), setting temperature is MAX. HOT, ambient temperature is below 10°C (50°F) and blower switch is not OFF) are met.

The PTC heater assembly controls PTC heater lines by electric load or the amount of inverter with converter assembly (PCU) output. Therefore, troubleshooting should be performed with other electric components off.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. INSPECT PTC HEATER ASSEMBLY

(a) Remove the PTC heater assembly.





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

Standard Resistance:





Text in Illustration





NG -- REPLACE PTC HEATER ASSEMBLY Disassembly
OK -- Continue to next step.

2. CHECK HARNESS AND CONNECTOR (PTC HEATER ASSEMBLY - BODY GROUND)

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





Standard Resistance:





Text in Illustration





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

3. CHECK HARNESS AND CONNECTOR (PTC HEATER ASSEMBLY - INTEGRATION RELAY)

(a) Disconnect the PTC heater assembly connector.





(b) Disconnect the engine room relay block and junction block (integration relay) connector.





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

Standard Resistance:





Text in Illustration





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

4. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - INTEGRATION RELAY)

(a) Disconnect the A/C amplifier connector.





(b) Disconnect the engine room relay block and junction block (integration relay) connector.





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

Standard Resistance:





Text in Illustration





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

5. REPLACE INTEGRATION NO.1 RELAY

(a) Replace the integration relay Removal.

HINT
Since the integration relay cannot be inspected while it is removed from the vehicle, replace the integration relay with a new or a known good one and check that the condition returns to normal.

(b) Check if the same problem occurs again.

OK:

Same problem does not occur.

NG -- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Air Conditioning System

OK -- END (INTEGRATION RELAY WAS DEFECTIVE)