I have 1 thermostat for furnace and 1 for ac, both only have 2 wires. Can I hook them into one programmable thermostat? The new thermostat can control both heat n ac.

One issue you will have is trying to modulate 2 control boards, if so equipped. Typically there is only 1 board on a combined heat and AC unit. Sounds like you have a single stage, single speed set up. Most likely you will need more wires and piggyback them at the thermostat because you will need 2 X 24VAC for the boards. I would get the schematic for the Thermostat you wish to use and then their website for support.