rattling noise during cold weather

Is it from the blower? You may need a new blower motor or that may be debris in the impeller fan. If not from the blower, it could be an actuator getting a bad signal or a door getting loose. Get to a Nissan specialist for help, I don't have enough information to narrow it down much. Here's a directory link for you: http://repairpal.com/nissan-repair-in-lawrenceville-georgia

We have done quite a few of these, the acuator gets stuck. The actuator needs to be replaced on 90% of these. If you like to bring it by we can do a free diagnosis & estimate for you. Bring this e-mail in with you for free service per Joe