When i go to turn my heater or defrost on in my car it just blows cold air out and i don't know why.

Check the valve in the hot water line that goes to the heater core. It it's vacuum operated, you could have a broken or leaking hose. The plunger inside the valve may also have stuck in the closed position.

Thermostat. That is the first thought. I don't think it would be the heater core itself because you would know if that was going. Usually with antifreeze leaking into the passenger side floor and getting a mist that smells like maple syrup through your vents. And just for $hits and giggles, I would check any kind of fuse that deals with heating. But I doubt that is the problem.

could be but not necessarily,low coolant level,Check when vehicle is shut down and has cooled down completely to prevent scalding danger from hot coolant. remember safety first

It,s broken.

Unfortunately, I used to own the exact same car six years ago.

I purchased it brand new, fully loaded and the moment I mailed the final car payment, it went totally NUTZ!!!

It developed a personality of its own!

What a headache, heartache & a--ache, if you will!

Everytime I fixed or replaced one part, something else went wrong!

It got to the point, I was spending more money repairing it, than driving it!

My advice to you: Don't fix the heater, buy a new car!

I beseech you!

DO NOT PASS GO, DO NOT COLLECT $200.00!!!

It's only a matter of time before the car shuts down completely & you are on the expressway/highway, or some remote place 40 or 50 miles from your residence.