SsangYong Stavic / SsangYong Rodius (2005 year). Service manual — part 296

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PTC (POSITIVE TEMPERATURE COEFFICIENT) SYSTEM

1. GENERAL INFORMATION

The supplementary electrical heater is installed in D27DT engine equipped vehicle as a basic equipment. The PTC
system is operated according to two temperature values measured at the coolant temperature sensor and HFM sensor.

This device is mounted in the heater air outlet and increase the temperature of air to the passenger room.

Because PTC system is heated by electrical power, high capacity alternator is required. (Alternator of 12V 75A/90A has
changed to 12V 140A)

Non-opeational Condition

- During engine cranking

- When too low battery voltage (Below 11V)

- During preheating process of glow plugs

PTC Assembly

Engine ECU

○

○

○

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PTC Relay

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Characteristics of PTC

2. PTC COMPONENTS

Radiator Element

Frame

Spring clip

PTC-Ceramic

Connector

Heating type

Heating efficiency

Element

Weight

Durability

Safety

Advantages

P.T.C Heater

Air heating type

Excellent

Ceramic PTC (BaTio

3

)

approx. 500g

Excellent

Excellent

- Stable output regardless of voltage changes

- Block the overcurrent with switch effect of PTC element

- High heating capacity in a moment

- Excellent durability of heating element against high current

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3. PTC OPERATING PROCESS

PTC Operating (ON) Condition

The operating condition of PTC is controlled by two step.

Generally, ECU control the power relay for PTC depending on the coolant temperature and ambient temperature sensor.

1st step (Initial PTC operating condition)

When coolant temperature < 15°C, PTC is operating (ON).

When coolant temperature

≥ 15°C, tow conditions decribed below must be satisfied.

2nd step (Coolant temperature: 15°C)

When coolant temperature 65°C

≤ and ambient temperature ≤ 10°C PTC operates (ON)

When coolant temperature 65 ~ 60°C and ambient temperature -10°C ~ 0°C PTC operates (ON)

When coolant temperature

≤ 60°C and ambient temperature ≤ 0°C ~ 5°C, PTC operates (ON)

PTC “OFF” Condition

Airconditioner blower switch OFF

Ambient temperature sensor error (wiring short or open)

When engine craking

Battery voltage is lower than 11V

When preheating the engine (Glow indicator “ON”)

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Circit Diagram