Quick question, first I didnt have air but on defrost, so I replaced the vacuum selector switch thing, which gave me air in my vents and down below again.

I still get a hiss when controlling the Cool or Hot lever, I can feel where it is coming out and it is on the left side where there are two hoses connected to the unit. It appears to me that this is a part of the actual unit? As in that part cant be replaced? Anyone give me a clue on this one?

Thanks for the help! Making progress.