Please advise re Air Con - VERY NOISY!

[siberpasta]

Hi there. I really would appreciate some advice.

I have a 52 Reg TD4 Freelander Auto diesel. Tonight I went to regas the aircon (as it was totally empty when i bought it two months ago), and after it was gased, when i press the aircon button, it makes a real loud whiney noise. When i turn the aircon button off, the noise dissapears. I can still use the fan and normal heater without the noise - the problem is only when i turn the air conditioning on (and the aircon is now very cold so it is working - just unbelievably noisy).

When i accelerate down the road, it is VERY noisy. I havent used the aircon before, as it was empty.

Could the problem be that the aircon belt is no good, or is it likely to be the compressor?

This car recently had the engine taken out so that the auto gear box could be repaired. Is it likely that something isnt right after this work, a nut not tightened, belt worn?

I really would appreciate any ideas you may have.

Many thanks, Simon