motor reving an no heat

First I would make sure your the cable that works your choke on your throttle body did not come off. That will cause the choke to stay open and suck in to much air and cause it to rev real high. Had it happen to me before. If that is ok clean throttle body with throttle body cleaner spray carbon build up could be not letting the choke close all the way this can also cause engine to rev high. As far as just cold air coming out of your vents there is a switch over door in your heater box that opens to heater core when there is a call for heat then it closes the other way to A.C evaporator when there is a call for A.C. There is a cable that controls this door under dash by glove box. The cable or linage may have come off.