Illuminated Engine management light

[RingSpanner]

Hi again ,my engine malfunction light is ON on my X type 2.5 v6 petrol ,2001 reg, Originally my code scanner showed fault P1111 as the problem, but having searched online I found that this is an engineers code following maintenance work. confusing as NO maintenance work had been carried out on my car. Anyhow I turned out the engine management light using my code scanner to do so. on restarting the engine all seemed ok .but after a minute or so of driving -the Engine management light came back on . After rescanning with my code reader the Fault now came up as P1647. on checking this relates to Air Conditioning Compressor Temperature sensor fault., But does anyone know where it is situated as I don't have a clue ---please help ---Thank you ---RingSpanner