My A/C hisses and blows warm/hot air when stopped at a red light, stop sign and just parked. It only blows cold air when moving. When its not moving and blowing warm/hot air it hisses. Ideas? Cost to get fixed?

 

Could be multiple things, but my gut tells me that you're low on freon. If you have Autozone in your area you can rent an A/C gauge set for free. You only have to give $40 deposit and you'll get it all back when you return it. Hook it up to your low and high side service connector. Make sure both valves are closed at the gauge. Start the car, switch on your A/C with high blower. Leave it running for about 10 minutes.
Post your low and high side reading in this post with outside temp at the time of reading. That should give us a good starting point.