Have you checked the function of the blend door? It's easy to check. I made a little video by the way if you want to look at it. There's a pivot point for the blend door you can easily see just by looking under the bottom of the HVAC tubing, I hooked channel locks to mine so you can see it and mine was actually blocked a little I helped it close and think this may fix my problem but I can't tell as it's warm today. I'll know Friday or so though...