I had to replace the part that you sand paper down. Since then I have had problems with stat, replaced it now, and my next problem is that when I turn on the a/c, heat comes out I have a a/c and heating expert but mainly works on commercial units not a trailer unit. I need help bad or instructions of some sort. The only thing he can think is the heat pump and I am praying it is not that, I have already put enough money in this red t products unit. Any one that may have a answer please help me. Thank you so much.