Hey guys I'm new to the group. But I have a question about my 04 titan. Since it's been so cold here in Texas lately I usually try to go out and start my truck before work every morning. I turn on the heater or defroster and let it idle for ten minutes. But when I come outside, it's blowing ice cold air! It continues to do so until late I click it into drive. Then it blows hot air just fine. Any ideas as to why this is happening?