Operation

OPERATION

General

Feed from the positive battery terminal (C0192) is supplied to fusible link 5, fusible link 1 and the main relay (C0632) on an R wire. All are located within the engine compartment fuse box.

The earth path for the main relay coil (C0576) is controlled by the Engine Control Module (ECM) (C0603) on a WK wire. The energised main relay provides a feed to fuse 4, which is also located in the engine compartment fuse box. For more details on main relay operation, refer to the Engine Management Systems – EDC section of the System Description and Operation Workshop manual.

Fusible link 1 is connected in series with fusible link 2, fuse 8, and fuse 9 which are also located in the engine compartment fuse box. Fuse 8 (C0576) provides a constant battery feed to the heater blower relay (C0153) on a GN then GW wire. Fuse 9 provides a constant battery feed to the compressor clutch relay, 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 (C0586) provides an ignition feed to the following on G then LGS wires:

The blower motor switch (C0058). The fresh/recirculated air switch (C0750). The fresh/recirculated air motor (C0006).

A/C Master Switch

When the blower switch (C0058) is turned to position 1 or higher, it provides a feed to the A/ C master switch (C0275) on an SW wire. If A/C is requested, the switch (C0275) provides a feed to the instrument pack (C0233) on an SK wire. When the instrument pack receives an A/C request from the switch, it informs the ECM (C0331) via the CAN BUS on YN (Low) and YB (High) wires. The A/C master switch is mounted on the centre console and is earthed (C0275) on a B wire.

For more information on the CAN BUS, refer to the Communication Databuses section of the System Description and Operation Workshop manual.

Compressor

When the ECM (C0331) receives an A/C request signal via the CAN BUS, it will energise the A/C compressor clutch relay by providing an earth path for the relay coil (C0576) on a UB wire. A feed from fuse 9 of the engine compartment fuse box is now able to flow across the energised relay (C0575) to the compressor clutch (C0127) on an R wire.