PTC HEATER

id071100002700


Purpose

•  The PTC heater is a supplementary heater which uses electricity as the heat source to improve the heating performance of the A/C unit temporarily when the diesel engine is cold.

Function

•  The dash-electrical supply unit performs operation determination and controls the PTC heater.
•  The PTC heater warms the air passing through the A/C unit by generating heat.

Structure/Construction

•  The PTC heater consists of a film-like heater element, aluminum fins, and brass plate, and it generates heat by passing electric current to the heater element.
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•  The electrical resistance of the PTC heater has a tendency to increase in proportion to the heat generation of the heater element (PTC element).

Operation

1.  When the ignition is switched ON (engine on), the dash-electrical supply unit receives (1) signals from each part.

Part

Signal

Condition
Climate control unit
Airflow temperature setting signal
Target temperature not controlled
PCM
Ambient temperature signal
Less than 20 °C {68 °F}
PCM
Engine coolant temperature signal
Less than 70 °C {158 °F}
PCM
Engine status signal
•  10 s or more have elapsed since engine was started
•  During i-stop operation (engine stop control)
PCM
Charge warning light illumination request signal
Not received

2.  When all of the conditions are met, the dash-electrical supply unit performs PTC heater operation determination (2).

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3.  The PTC heater operation determination calculates (3) the PTC heater output value (generation amount and operation time) based on the ambient temperature and target temperature.

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4.  The dash-electrical supply unit outputs (4) a PTC heater operation signal based on the calculated PTC heater output value.