Why is a.c. controls making loud noise

There really isn't enough information with this question to answer it. If the a/c sometimes goes on and off by itself, there may be an electrical problem or a problem with the a/c control head. This needs diagnosis by a competent shop. Cliff's Car Tech will be happy to do this for you. Hopefully you can provide some more information as to under what conditions the noise and intermittent operation of the a/c occurs. Thanks!