With the engine off, take the bonnet off and look down the drivers side of the engine - you'll see a drive belt and the bottom component is the climate compressor.
Carefully put your hand down and see if you can turn the middle part of the compressor - the belt should remain stationary and there should be no movement of the centre of the compressor. If it moves, it's shot!
Apart from this, there's many other factors that can cause the climate to not work, but a scan is the only way forward.
Cheers,
Mike