My car was making warm air last night. A guy from the body shop pulled it out of the shop for me. Let it sit and idle while we go inside and finish some paperwork. When i got it in it was warm and all night that night it was making warm air. Now 24 hours later, i had to drop off something for my girlfriend, and it was not making any warm air, it was friggin cold. The temp needle was in its normal position too right in the middle, still no heat. I just put in a new thermostat maybe 6 months ago.