Wow, I did what you said. Maybe having automatic termperature control makes it different. First, the cover panel doesn't come off very easily; there's losts of stuff in there. Second the heater inlet is connected to a duct (insulated on the outside) that is under a bunch if wire and cables. All of this scared me off. I'm going to get my shop to look at it, since I can't get the AC compressor to kick on, anyway.