I did some searching and I have a general idea but I wanted to talk to you all about things first. The last 2 days while driving into work I have had little to no heat. Today it was about 20 degrees out while I was driving to work, and I ran the truck for about an hour between sitting in traffic and taking my little one to daycare. When i got into my parking lot I checked my fluid level in my radiator overflow box and it was no more than .25 lower than the fill line. What was really weird was that just for kicks i touched my radiator cap(I know your not supposed to do that, idk what possessed me to do it) and it was cold. Not like freeze your tongue to a flag pole type cold but it wasnt hot like I was expecting it to be for having just run my truck for an hour. I havent checked the doors that control the heat/cold input in the truck (forgot what they are called). Also I plugged in my OBD2 scanner and check it for what my coolant temp was at and it was reading at 200 degrees, IDK how accurate that actually is but that is where Im starting at. So basically I know i need to check the doors, but should I change my thermostat and flush the system? Sorry for the long post I am just puzzled about what to do and its dang cold outside!