On other cars like sunfires that have no ambient sensors still disable the a/c when its cold out( they dont have factory remote starts so it must be to protect the compressor or something)...even my old one that I installed a/c using factory parts did the same. I think its something to do with the cycling switch knowing the temp.
So with this is a possibilty that the climate control will turn on the heat when the pcm data says the a/c is disabled this would eliminate the need for a sensor on 3 button models...with the 5 button dic I would imagine this will override all this and make it more accurate for choosing the temp.