We have a 2002 Beaver Patriot and are having problems with our heater/defroster system. We can only get cold air through the system. We pulled the electronic control knob, testing it, and sure enough it is okay. So the problem lies deeper in the system, Beaver rep suggested it could be at the other end and suggested looking at the heater system up on the firewall to move a lever on the heating pot and duct tape it in place so that it stays in the heat mode, especially through the winter. Anyone have such an experience and have recommendations as to how to identify the same?