Ptc Heater Operation Process; Ptc Heater Input/Output Factors - SSANGYONG Korando 2013 Manual

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5. PTC HEATER OPERATION PROCESS

The engine ECU controls the PTC (Positive Temperature Coefficient) heater system by adjusting the
power supplied to the PTC system according to the two measured temperature values from the engine
coolant temperature sensor and HFM sensor. This system is mounted to the heater air outlet in the air
condition system module and heats the air which flows to the passenger room. Since the PTC system is
heated by the electrical power, the electric load and alternator capacity is greater than the conventional
one. The PTC is not operated when a) the engine is cranking, b) the battery voltage is below 11 V, c) the
glow plug is being preheated.

1) PTC Heater Input/Output Factors

The ceramic PTC features that the resistance rises quickly in a certain temperature range. The PTC
heater has 3 circuits with power of 330 W. While only 1 circuit in the PTC heater is connected during
PTC1 operation, 2 circuits are connected during PTC2 or PTC3 operation.
The PTC heater operates as follows: temperature rises above specified level→resistance
increases→current decreases→calorific value decreases→temperature drops→resistance
increases→current increases→temperature rises.