Hi, I'm new here and I have a 1998 Dodge Stratus.
I bought it used in April, and the ac never came out of the right vent.

After some research, I am fairly certain that it's a vacuum leak somewhere. The ac only comes out of the defrost position 90% of the time. Sometimes it works right and comes out of the vent that I have it set to, but usually it just goes to defrost. There's not really any pattern to when it does this, and occasionally (if I'm lucky), it'll switch back to the vent I have it set to while driving.

I wanted to know how to find a vaccum leak, and if I should be looking under the hood or somewhere in the dash, and what one does to fix a vacuum leak.

Thanks in advance.

 

Welcome to DF
trace the vacuum line going into the bulkhead/firewall. Make sure the line is plugged in the vacuum tee at the motor, and then listen for a vacuum leak inside the car or remove the front control head and inspect the vacuum lines and cables if it has them.