The wires are pretty much straight forward.
You have a RED wire on R, it goes on R on the nest wall plate.
Green wire goes on G and controls the indoor blower fan. it goes on the G of the nest wall plate
The WHITE wire is on the W and goes on the W of the nest wall plate.
The YELLOW wire on Y goes on the Y of the nest wall plate. This turns on the compressor.
The Blue wire is on C and goes on C if the nest wall plate. This is the COMMON
The Orange wire on the O, goes on the O/B on the nest wall plate. This energizes the reversing valve of the heat pump.
Now the black wire, it is on W2. In normal system, W calls for heat, Y calls for Cooling, W2 is stage 2 Heat. We need to know either the programing of your current thermostat or take a look inside the indoor air handler.
Know this, with the R, Y, O, G, and C, you get the heat pump cooling and heating. We just need to understand better the W and W2. One of those will initialize the auxiliary or emergency heat, and the other one, I am not sure of. If you can post a picture of the outdoor unit manufacturer label and the indoor manufacturer label, I can look up those units and see what is what. Do you have a humidifier? That might be the other wire.
NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
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