I have now for the past week had a screeching noise from under the bonnet you know the one like the a belts loose, now as far as I can tell the noise sounds like it's coming from the large bottom pully, does anybody know how I can tighten up the belts to stop this.

 

The belts are adjusted in different ways. Find out if its the aircon one or the alternator one.

Both belts have threaded adjusters.

 

I know this is going to sound daft but wouldn't the aircon belt only screech if the aircon was on ?? or does the belt run all the time