Question A4 Cab V6 TDI Aircon not working

Have noticed aircon is no longer supplying any cold air. Controls seem to be working fine Auto light on without Econ light. Fan operates at maximum level to try and reduce temperature but no cold air to achieve required temperature. Car was recently serviced by main dealer including full V6 cambelt and waterpump change. I suspect that aircon has not worked correctly since the service. Given the large amount work involved in this service is there a logical reason why something may have been disturbed or is it just an unfortunate coincidence. Have read elsewhere of a similar incident which involved a loose wire between a relay and the magnetic clutch. Any experts out there with a view on this? Thanks.