5 Button means you have old style. Odds are the reversing electric coil is bad. Dometic sells 2 coils as a replacement. They do that because they used 2 different types and they have no way to tell which is which. Once you get the coil it will be obvious which is yours. I doubt the main control board is the problem. As Chris stated, your model it takes power to energize for COLD. So, if you are running in cold mode and it switches to HEAT, that would tell me the energizing coil is dropping out, even tho it has power. Doug
