2002 Wrangler Sport Blowing COLD air.

2002 Wrangler Sport 152K never had an issue until now. It's been chilly lately here in NY and I've been starting to use the heat...Well I started up the car, let it warm up (it's fully warmed when it reached 210 on the thermostat/temp gauge) and I turned the heat on to floor/vent. Cold Air. I turned it off, back on same thing. Slowly checked each setting, they all work but continues to blow cold air. So i left it on low and put the car in drive and proceeded to work..about half way down my driveway it then gets hot air. I thought maybe a one time thing...well I was wrong.. it did the same thing every time I start her up now. Sometimes it's a pain because it'll stay on cold and not go to hot. She's never done this since I drove her off the lot new.

Any ideas?