Heater dial works fine ac dial doesn't work, Heater will turn on and off byitself

Hello, there's probably a history you may not be aware of. This vehicle being 18 years old -- it's too hard to know what is going on without doing a physical inspection. Is there a wiring issue? Have modifications been done, such as with a radio installation in the same area? I suppose the control head could have a concern, but it's a wild guess and testing should be performed. Hands on by a skilled technician near you. www.repairpal.com/repair-shops My biggest concern is that this could be a fire hazard.