Who can I contact about a stuck climate controller or can I purchase needed part on 2006 Nissan Armada

Two weeks ago the automatic air controller would not go up or down I can turn temp levels up/down but I can not turn it off.

Asked by for the 2006 Nissan Armada
this may be a circuit issue and not a controller issue i suggest a diag and est b4 replacing any parts on a guess