Kia Rio: Heater / PTC Heater

Kia Rio 2017-2024 YB Service Manual / Heating,Ventilation, Air Conditioning / Heater / PTC Heater

Description and operation

Description

The PTC (Positive Temperature Coefficient) heater is installed at the exit or the backside of heater core.

The PTC heater is an electric heater using a PTC element as an auxiliary heating device that supplements deficiency of interior heat source in highly effective diesel engine. The electric heater heats up the interior by directly heating the air that passes through the heater. The name itself implies that the element has a proportional resistance change sensitive to temperature.

Operation Principle

ECM outputs a PTC ON signal and operates PTC relay 1. Then heater controller operates PTC relay 2 and PTC relay 3 with an interval of 15 seconds.

However, PTC relay 3 can be operated while battery voltage is above 12.4V.

Operating Condition

PTC heater operates according to the following conditions;

•	Battery voltage: 12V or above

•	Engine: Running

•	Ambient temperature and coolant temperature

Ambient Temperature	Coolant Temperature	PTC Operation
Below -10°C (14°F)	Below 80°C (176°F)	ON
15°C (59°F)	Below 70°C (158°F)	ON
20°C (68°F) or above	-	OFF
-	80°C (176°F) or above	OFF

Repair procedures

Inspection

Operating Logic Test

Inspect the PTC operation by confirmation logic as follows ;

Entering

(1)	Set the Vent, Bi-Level, or Floor mode and maximum heating position.

(2)	Turn off the blower switch.

(3)	Press the intake (recirculation) button 5 times or more.

(4)	Indicators of entire button are continuously flashed with an interval of 0.5 seconds (MANUAL). Graphics of the entire LCD display continuously switch on and off with an interval of 0.5 seconds (FATC).

(5)	Confirm the PTC operation by turn on the blower switch

(6)	Each PTC relay is operated with an interval of 3 seconds.

(7)

The logic test will be automatically cancelled after 30 seconds.

In addition, it can be cancelled by followings;

•	Operating any switch except the blower, temperature and off switch

•	Ignition switch OFF

Cancellation

•	Operate any switch except the blower, temperature control, mode off switch.

•	Turn the ignition switch OFF.

•	The test is cancelled automatically after 30 seconds.

3.	If the PTC is not operated, substitute with a known-good PTC heater and check for proper operation. If the problem is corrected, replace the PTC heater.

Operating Test

This test should be performed in the PTC ON conditions.

1.	Run the engine.

Check the current on wiring with a clamp multi tester.

Pattern	Current (A)
PTC 1 ON	0.1 ~ 33
PTC 2 ON	0.1 ~ 33
PTC 3 ON	0.1 ~ 33
Total	0.1 ~ 100

3.	If the current is not specification, inspect related wiring.

Resistance Test

1.	Turn the ignition switch OFF.

2.	Disconnect the PTC heater connector.

Measure the resistance between terminal 1, 2, 3 of PTC heater and ground line.

Resistance : 0.3 ~ 1.5Ω

PTC 1

PTC 2

PTC 3

4.	If the measured resistance is not specification, replace the PTC heater with new one.

Replacement

1.	Disconnect the negative (-) battery terminal.

2.	Remove the console assembly. (Refer to Body - "Floor Console Assembly")

3.	Disconnect the PTC heater connector (A).

4.	Remove the PTC heater core (A) after loosening the PTC heater mounting screws.

5.	Installation is the reverse order of removal.

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