Thats what an automatic climate control system does. It attempts to maintain the set temperature inside the car. If it's 32 degrees inside the car and the temperature is set to 70, then the climate control system will turn on the heat until the temperature inside the car reaches the set temperature, after reaching the set temp, the heat should go off or the blower should lower it's speed. This was the same is my Maxima and my g37. My temp stays at 72. In my g it stayed at 78 because anything lower and it would feel like the north pole inside the car. But I stay in Miami and deal with 85+ degree weather almost year round. When it does get cold, I don't have to change the set temp. If it's significantly cooler than 78 degrees outside and in the car then the heat will come on. If its hotter, than the ac comes on. The only time I could get the heat to come on in the summer was by setting the temp between 88 and 90. I'm guessing in winter is vice versa for the colder climates, you have to set the ac to one of the coldest settings to override the climate controls. You can also try turning off auto.