We have a coleman evcon blend air II furnace. The blower motor will not kick on when the a/c is turned on, but will kick on when switched over to heat. The outside unit is working. We have replaced the thermostat and a relay switch and still no fix. Any ideas?

Has the blower motor in the furnace been replaced recently? If so the wiring could be wrong on the circuit board. The heating and cooling relays are different.

No it hasn't been replaced recently. The a/c was working and we left and came home and it was so hot in the house.