Kia Carens: Heater / PTC Heater (Diesel only) Description and operation
The PTC (Positive Temperature Coefficient) heater is installed at the exit or
the backside of the 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 the 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 : 12.4V or above
|
• |
Ambient temperature and coolant temperature
|

Replacement
1.
Disconnect the negative (-) battery terminal.
2.
Remove the heater and blower assembly.
(Refer to Heater -" ...
Inspection
Operating Logic Test (Manual only)
Inspect the PTC operation with the confirmation logic below :
1.
Entering
(1)
...
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Brake Booster Operating
Test
For simple checking of the brake booster operation, carry out the following
tests.
1.
Run the engine for one or two minutes, and then stop it. If the pedal
depresses fully the first time but gradually becomes higher when ...