PTC Heater (Diesel Only)

Description and Operation

Description

The PTC (Positive Temperature Coefficient) heater is installed at the outlet or rear side of the heater core. The PTC heater is an electric auxiliary heater that compensates for the lack of internal heat source in high-efficiency diesel engines. The electric heater warms the cabin by directly heating the air passing through it. The name implies that the element has a proportional change in resistance that is sensitive to temperature.

Operating principle: The ECM outputs the PTC ON signal and activates PTC relay 1. The heater controller then turns on PTC relay 2 at a 15-second interval. The PTC heater operates under the following conditions:

• Battery voltage: 13 V or higher
• Engine is running
• Ambient Temperature and Coolant Temperature

Repair Procedures

Inspection

Operation Logic Check (Manual Only): Check PTC operation using the confirmation logic below:

1. 1
   Input

   1. Set the mode to FLOOR.
   2. Set the temperature to MAX HOT.
   3. Turn the blower switch off.
   4. Press the intake (recirculation) button 5 or more times.
2. 2
   Forced Operation

   1. Without A/C: The Intake button indicator will blink at 0.5-second intervals for 30 seconds. With A/C: The Intake button and A/C button indicators will blink at 0.5-second intervals for 30 seconds.
   2. PTC2 and PTC3 will operate when the blower switch is turned on.
      • PTC2 and PTC3 will operate at 3-second intervals.
      • PTC2 and PTC3 turn off simultaneously when the blower switch is turned off.
      • Only PTC2 and PTC3 will operate forcibly.
3. 3
   Cancel

   1. Select the A/C or intake (recirculation) switch.
   2. The test is automatically cancelled after 30 seconds.
   3. Turn the ignition off.
4. 4
   Start the engine.
5. 5
   Check the current in the wiring using a clamp-type multimeter.

   Pattern	Current (A)
   PTC 1 ON	0,1 ~ 33
   PTC 2 ON	0,1 ~ 33
   PTC 3 ON	0,1 ~ 33
   General	0,1 ~ 100

6. 6
   If the current does not meet the specification, check the related wiring.
7. 7
   Turn the ignition off.
8. 8
   Disconnect the PTC heater connector.
9. 9
   Measure the resistance between terminals 1, 2, 3 of the PTC heater and ground.

   Resistance: 0.3 - 1.5 ohms

   

   1. PTC 1
   2. PTC 2
   3. PTC 3
10. 10
    If the measured resistance does not meet the specification, replace the PTC heater with a new one.

Operation Logic Check (DATC Only): The operation logic can be confirmed using GDS. Operation Test: This test must be performed with the PTC heater ON. Resistance Test

Replacement

1. 1
   Disconnect the negative (-) battery terminal.
2. 2
   Remove the console side cover (A). [LH]

   

3. 3
   Disconnect the PTC heater connector (A).

   

4. 4
   Loosen the PTC heater radiator mounting screws (A).

   

5. 5
   Remove the PTC heater core (A).

   

6. 6
   Install in the reverse order of removal.