Air conditioning (page 3 of 3)

Fuse 7 of the engine compartment fuse box (C574-1) supplies a feed to the main relay coil within the engine management relay module (C154-6) on a brown/light green wire. If the engine is running, the ECM (C635-17) provides an earth path for the main relay (C157-3) on a blue/red wire. This energises the main relay and allows a feed (C154-3) to flow to the condenser fan relay coil (C1212-85) on a brown/orange then slate/blue wire.

The earth path for the condenser fan relay (C1212-86) is again controlled by the ECM (C634-3), this time on a slate/black then green/white wire. This energises the condenser fan relay, and allows the feed from fuse 16 of the passenger compartment fuse box (C581-12) to flow across the relay (C1212-30 & C1212-87) and onto the condenser fan (C280-1) on a blue/purple wire. The condenser fan is earthed (C280-2) on a black wire.

The compressor will only operate if a number of conditions are met, and is controlled by the compressor clutch. The clutch will only allow the compressor to operate if:

• The engine is running.
• The refrigerant pressure in the high pressure line is within the set limits.
• The temperature within the system is within the set limits.
• Excessive engine temperatures are not reached.

Assuming all these conditions are met, the compressor clutch relay will be energised by the ECM. Current will flow from the relay (C1213-87) to the compressor clutch (C182-1) on a brown/pink wire. The clutch is earthed (C182-2) on a black wire. This engages the compressor clutch and drives the compressor.