After driving my '94 cabriolet a few blocks, heat begins pouring from the vents and it soon becomes uncomfortably hot. The rotary heat control knob seems to have no effect. I've checked the clips located in the footwell, and the cables are firmly connected. I've discovered that turning on the AC for a couple of seconds corrects the problem, turning off the heat. Any ideas what the problem might be.
Solved the heater problem. One of the electrical connector plugs on the back of the heater control panel had worked lose. When I reseated the plug, the problem disappeared. What I learned is that when there is no signal telling the system what to do, it defaults to heater - a safety feature to prevent people from freezing to death. Once the signal was reestablished, the system then responded to the temperature set on the control panel.