Why isn't my AC Blowing cold air?

Unfortunately there are many possibilities as to why an AC system is not functioning properly . This ranges anywhere from a blown fuse all the way 2 major component failure. I would suggest taking it somewhere and putting gauges on it to see if it has any freon in the system. Then go from there.

was the A/C working before you had the heater core replaced? if so take it back to who ever did that work,ask them to check it as stated in answer #1.that heater core job is not bad on that car as compared to say like my F150.yours is a couple hours of work compared to around 8 hours plus on the F150.i believe i would have bypassed the heater core until fall weather got here,and made sure the A/C was working for the summer.