Operation CHARM: Car repair manuals for everyone.
Hosted by mcallihan.com

System Protection

Power to the compressor clutch may be cut should either the engine management or air conditioning control systems detect certain conditions; these conditions may be caused by Fault or Demand and can be classified thus:

Fault
- Engine coolant overheat.
- Refrigerant excessive pressure.
- Refrigerant, insufficient pressure or low charge weight.
- Speed differential between compressor and crankshaft caused by belt slippage or compressor seizure (indicated by A/C state lamp flashing once per second)-12 cylinder engine only. This feature is called, 'lock sensing'.

Demand
- Engine maximum power requirement
- Electrical system drain at engine idle.