Since its now quite cold out, I learned something about the HVAC during remote-starts:
If I start my car in the morning near or below freezing, it turns on the front and rear defrosters. After driving the car for a while, if I use remote start again, it turns on the AC. Keep in mind my car has the 3-button DIC. I think what is happening is that the only temperature references the car has are the coolant sensor, and the intake air temp sensor, both of which are skewed by running the car. I'm going to try installing just the ambient air temp sensor on my car and see if that fixes it.
