When you are installing a thermostat on MOST residential and commercial heat pumps, typically the orange wire goes to the reversing valve. However, when you are installing a lite commercial Carrier system there is no need to consider the reversing valve. So, what are we supposed to do with the orange (reversing valve) wire?  You will not use it because the system controls the reversing valve on its own.

The defrost control board that Carrier utilizes on their lite commercial products has logic built into the board to take care of the reversing valve(s), you simply tell the unit if there is a need for heat or a need for cool. When these systems receive a call for Y1 or Y1 & Y2 then the defrost board will energize the revering valve(s) as needed. When the systems are given a W1 call for Heat then the unit will crank up in high stage. The unit only has one refrigeration heating stage even if it is a “2 stage” unit. The “W2” terminals on split units are actually not inputs but rather outputs to engage the electric heat strips when the system goes into defrost; on the package units the “W2” is an input and it engages the electric strip heat if equipped.