Well i tried turning my heat on today and it wont slide over to the red side. Its a 5th gen with JRSC. Im pretty sure the heating units on the 4th and 5th gens are the same. Why would this happen? and how do i fix it?

 

I'm trying to think of how to describe this. Near the firewall there is a valve. When you turn the thing from cold to warm it moves that valve. It might be stuck. I am not sure if there is also a butterfly valve type thing inside though. If there is I would guess you got some crap in there. It has happened to me before.