2001 TDI 2.5 ACV, as the tittle describes at Idle Air Conditioning stops, Idle up AC Back On, i mainly commute on the Freeway so its on the whole time only at a set of lights AC stops, i have done some research and i have been told by an Car Ac guy its the idler and the only thing is i have no idea where its located on the engine itself and how easy is it to change, some one else suggested i may have a hose leak (air) but i have replaced the hoses recently (is there a way to check air leakage) also when at idle and press the ac button (not fan but the actual ac on) the idle stays the same apparently its supposed to increase the idle rpm, is this still the idler.....

any help much appreciated or if i need to answer any other details please let me know.