I've encountered the same problem in some of my flights. The implicit SOP in our company is to switch the HOT AIR Pb off. Recently, I found a senior training captain resort to pulling out a couple of CB's in the rear panel and resetting them, thereby solving the issue. If I remember it right, those were the cb's with the label ZONE TEMP CTL sys 1 & 2 in the rear CB panel. However there's mention of such a procedure in the QRH.