2005 Passat AC cooling issue

Hi THere
New to the forum, bought a 2005 passat wagon 2.0tdi and when summer came around last year found the ac not cooling very well. Fan is working fine however there is very little cold air coming through, looked around the net and there seem to be issues with the ac units, any input as to where I should start looking?
VW can check the charge of the refridgerant and look for a leak, what about the clutch on the ac? Would like to get this in order before the hot weather arrives. Thanks.