DESCRIPTION

Vehicle climate control via the heater unit is insufficient when the engine is cold.

There is also an optional additional heating system which is activated when the engine is first running, depending on the temperature of the engine coolant.

The system consists of an additional heating device, located inside the heater unit: this device contains two resistors (PTC1 - 250 W and PTC2 - 500 W).

The operation of the resistances is controlled by the climate control system control unit which operates either only one of them or both thereby providing gradual heating with a maximum power of 750 W according to a control logic that depends on:

- the outside temperature (below 20°C)

- the temperature of the engine coolant (about 70°C);

- the engine speed (which should be above 700 rpm);

- the battery voltage (which should not drop below 12.6 V).

For more details

    See descriptions 5040 AIR CONDITIONING CASING AND COMPONENTS

The power supply for one, two or three resistors is operated by means of two relay switches located on the actual heater unit:

- 1. Level: activated by the first relay switch (250 W);

- 2. Level: activated by the second relay switch (500 W);

- 3. Level: activated by both relay switches (750 W)

The power supply line is protected by two fuses located in a dedicated engine compartment fuse box.