199002870 - E6015 ADDITIONAL HEATER - DESCRIPTION (Manual air conditioning)

DESCRIPTION

Vehicle climate control via the heater unit is insufficient when the engine is cold.On these versions there is also an 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 resistances (PTC1 - 250 W and PTC2 - 500 W).The operation of the resistances is controlled by the climate control system control unit which operates either just one of them or both thereby providing gradual heating with a maximum power of 750 W according to a control unit that depends on:- outside temperature (below 20°C)- the temperature of the engine coolant (about 70°C);- the engine speed (which should be above a 700 rpm);- the battery voltage (which should not go down below 12.6 V).For more details    See descriptions 5040 AIR CONDITIONING CASING AND COMPONENTS The power supply for one, two or three resistances is operated by means of two relays located on the actual heater unit:- 1. Level: activated by the first relay (250W);- 2. Level: activated by the second relay (500W);- 3. Level: activated by both relays (750W)The power supply line is protected by two MIDI maxi fuses located in a special additional fuse box at the side of the battery.