A/C and Heat not turning on

I have a 1992 GT I bought used never got to use the A/C or heat. I was told that neither worked but the Heater Core needed to be replaced. So during that wonderful 8hr excursion before putting the dash back together I tested the blower by connecting it to a battery. I was happy it turned on and spun. Fast forward dash is in everything is connected and when you turn the heat or a/c on low, med, or high nothing happens. Could it be my resistor or the switch? And if it is the resistor do I have to take the dash out again. It's located on the blower box correct. Any help is appreciated thank you.

Thank you Ill check it out. I thought that was the case it would blow on high only. I should also check the actual A/C switch maybe I need a new one. Thanks again

Already checked fuses, I hope when I put the dash back from doing the heater core I didn't mess something up. I have off tomorrow so I'm going to do the resistor it can’t hurt. Thank you I'll let you know how it turns out.