a/c smell

after running the engine for a little bit and i turn on either the a/c or heat, the a/c will blow cold and the heat blows hot but it has a weird smell to it like somthing is burning. burning oil? has anyone else has/had this problem? does anyone know how to fix it?

I recently turned on my A/C (first time this year) and almost passed out due to the smell. I shut it off and opened the windows to air out the cabin. After checking everything out, I tried it again and it worked fine! I hope it's that easy for you...

EDIT: (Sorry - repost)

Does it smell like coolant? If it does, I would bet your heater core has a leak. Is the smell distinct with any type of ventilation on or is it just with the AC? I had the same problem this winter with my S10. One night the defrost wouldn't work and it smelled like coolant horribly. I had the entire interior minus the steering wheel and carpet out to replace it. Hopefully this isn't your problem.