You guys are great. With your help, I solved the heater problem. Thank you so much.
Yes, the air mix actuator on top of the heater box was stuck. I couldn't actually see this when I started the work this morning. There are only two small holes to see what is going on when I removed the glovebox. So, I actually did something unique. I drilled a few more holes in the metal so I could see what was going on. See before and after pictures.
The arm was stuck somewhere in the middle. So I pushed it straight / towards the left and the air got colder. So I then pulled it back towards the right and voila, the air got much hotter. I am saved for the winter.