CSUN Major Change?

Hello.
So I was accepted into CSUN as a criminal justice major, but Ive decided to do mechanical engineering, specifically aerospace. I was wondering if I am able to change my major once I enroll into CSUN. My housing application says to place the major that I would like, and with that it dorms me with people with a similar major. So can I put engineering and change my major to engineering even though I was accepted as another major? And if I do that will I face any repercussions? I dont have to take any early start classes or whatever, and I plan on taking Calculus at a local community college because the classes are free till im 18.