AC/Heater control question

[nate_g_2003]

Hey guys. Got a problem with my ac/heater control. The fan switch works fine, as does the inside/outside lever, and the middle lever (ac vs heat? I can't remember). The bottom lever, which controls the temp, is what is acting weird. When I move it from cold to hot, it will physically go all the way to heat, but it won't stay there. It comes back to the middle, which doesn't really give any heat/hot air. I'm thinking the cable may be messed up, or is this a flap in the box issue? I can move the lever over, and it feels like it wants to stay, but as soon as I let off, it goes to the middle. Any ideas?