General
The Positive Temperature Coefficient (PTC) heater replaces the Fuel Burning Heater (FBH) fitted to Td4 vehicles in markets of a moderate climate. The PTC heater, like the FBH, is an auxiliary heating system that compensates for the relatively low coolant temperature inherent in the diesel engine.
The PTC heater is an electrical heating element installed in the heater assembly on the downstream side of the heater matrix. For a more detailed description of PTC heater operation, refer to HEATING & VENTILATION - DESCRIPTION & OPERATION of the System Description and Operation Workshop manual.
Note. Cold climate specification vehicles still maintain the FBH.
Feed from the positive battery terminal (C0192) is supplied to fusible link 1 and fuse 10 of the engine compartment (C0632) on an R wire. Fuse 10 (C0575) provides a constant battery feed to the inertia switch (C0123) on a G wire. The inertia switch is a normally closed switch.
If the inertia switch hasn't been tripped, current flows across the switch to the fuel pump relay (C0575) on a GU wire.
Fusible link 1 is connected in series with fusible link 2, which is also located in the engine compartment fuse box. Fusible link 2 (C0571) is connected to the ignition switch (C0028) by an NR wire. When the ignition switch is turned to the 'ignition' position, current flows across the switch (C0028) to fuse 4 of the passenger compartment fuse box (C0588) on an SU wire.
Fuse 4 (C0585) provides an ignition feed to the blower motor switch (C0058) on a G then LGS wire.
The battery (C0192) also provides a feed to fusible link 1 (C1875) located in the fuse holder on an R wire. Fusible link 1 (C1875) provides a constant battery feed to PTC relay 2 (C0157) on an N wire.