Tech guy just told me furnace and AC were both running at the same time that's why no cold air from AC. He jiggled some wires inside thermostat, now I get cold air from AC, but neither it or the furnace will turn off when selected temp. reached... have to turn thermostat to off position. Am willing to buy new thermostat if you think that is the problem (and not something on the furnace itself since he did something in the basement also.) Honeywell RTH230B

Take the t-stat off the wall, and wire red to w for heat, red to y for cool, if they both work this way then you need a new stat

Thank you Joshdta. I did what you said, and it WAS the thermostat. Just came back from Menards, installed it, and all is well.

Great, glad you got it going.