[Arctic]

Originally Posted by SD1too

1. Open the bonnet and identify the compressor. On your diesel I believe it's underneath the alternator. It's driven by a ribbed belt around a pulley.
2. Start the engine and select 'Econ' on the heater/AC control panel. Observe the ribbed belt rotating the outside of the compressor pulley. Notice that the inside (a circular plate) is stationary. This is the compressor clutch.
3. Now press the windscreen demist button on the control panel and look at the circular plate (the compressor clutch) again. Is it rotating now?

This should show you how it works

https://youtu.be/cO8-DN1Amtk