Derek, Mine does the same, vent only for the hot days, but no heat for the cold ones. Which really doesn't make a lot of sense as while most of us tend to know when in the morning they're going to get into their cold car (and can set the timer accordingly), few of us know when we're going to get in the hot car late in the afternoon. Note that this would require an electric aux. heater, as cabin heat is taken from engine heat. But alas, I'm fairly (reasonably? mostly?) sure that mine doesn't have one.