3234617 - E6015 ADDITIONAL HEATER - Description

Description

The climate control via the heater unit is insufficient when the engine is cold, especially in Diesel engines which are slow to warm up.These engines may optionally be fitted with a supplementary heater system. This remains active from the moment when the engine is turned on until a certain temperature is reached.The system consists of an additional heating device, located on the engine coolant supply pipe to the heater unit.This device contains three spark plugs (similar to those used to preheat the combustion chamber).The operation of the heater plugs is controlled by a special control unit which operates either one, two or three of them giving 200W, 400W or 600W.

This control logic depends on:

• the temperature of the engine coolant;
• the electrical power available (the battery voltage is checked)
• the engine speed (which should be above a pre-set value)

The supply of one, two or three heater plugs is controlled by two relays:

• 1. Level: activated by the first relay;
• 2. Level: activated by the second relay;
• 3. Level: activated by both relays.

There is also a third relay/safety switch which interrupts the heater plugs supply if the contact to earth is not correct: the metal device containing the heater plugs is connected to the engine earth by means of a special loom. For more details,  see DESCRIPTION AND OPERATION: 5020L  additional heater . The control unit supply lines are protected by a fuse in the junction unit and by the fuse which protects other supplies controlled by the ignition.The safety relay supply line is protected by a fuse located in the junction unit, whilst the one supplying the resistors is protected by a special maxifuse.