Heating and A/C Problems in a '99 Chevy Blazer

I have a '99 chevy s10 blazer. The heat stop working in it and I put in a new heating core. however since that was put in my heat nor my a/c work. When I do turn on the heat it blows luke warm air and the ac doesnt work at all. I took it to a garge and they said that my heat dail to adjust the temp isnt gettin any juice to the dial. What do I do? The garge mentioned something about a heating diagram. Can anyone help me out?

Evan

Does the vehicle have automatic temperature control or manual A/C? With either system, the first step is check both terminals at all of the fuses with a test light when the key is in the RUN position.