OK. If I'm understanding this. Turning on the vent air or AC, the air from the vents is going from cold to warm on it's own. You said "no air", but I'm assuming it is still blowing from the vents.
Sounds like a possible blend door problem. If you are not knowledgable in automotive AC's, this one is best left to a professional.
Even to diagnois this will require going behind the dash. All of the controls and ducting are nicely hidden behind the dash area.
A 2006 with ? miles. At this age it could use a AC system checkup also.
, 5spd, LSD, Brembos
TTR rear sway bar
TTR front engine mount
GM Turbo Upgrade
Forge Motorsports BPV
Pedders Sportsryder springs
Flowmaster HP2 Shorty muffler
Glock 19 in pocket