Well, you can hook it up to work for cooling only. Hook your red wire to the rc terminal, remove the jumper between Rc and Rh, (if there is one), hook the green wire to G, and the yellow wire to Y. Leave the other wires unhooked and taped individually. The leftovers wires were for the 24 volts common (your new one must have batteries), auxillary heat, and the reversing valve used in the heat section of your system. Hopefully this works for you, Its kind of a shame you don't use the heat side. Make sure you turn the power off to your unit before wiring it. Good luck.