Air stops blowing cool my needle jumps to Hott.

Past few weeks I've noticed could be more three different spaced out times my air would stop blowing cold but not for long like it would kick back in and for a long period of time be fine to the point where I'm wondering did it even happen - well today the third time I looked up and noticed my needle was on Hott but like always goes right back to normal only thing my dad could tell me was what he knew wasn't wrong air filter was fine oil jus been changed and whatever liquid thing in the clear jug looking thing was normal