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Nest wiring question - No heat pump wire

I have a heat pump and the HVAC technician mentioned that I'm missing an orange wire, so he routed the green wire to the OB slot instead.

The current wiring configuration is:
Y1 - yellow wire
W1 - white wire
C - blue wire
Rh - red wire
OB - green wire

Both the heating and cooling functionalities work. However, I am not able to turn on just the fan. I live in a pretty vertical townhome so the upper levels are much hotter than the lower levels. I'd like to turn on just the fan to circulate the air.

Is there a way to do that with my current wires? I'm happy to sacrifice the auxiliary heating wire. I don't live in a very cold location so the auxiliary heat is not needed.
If that still doesn't work, is there a way to configure the wires for fan/heat in the winter and fan/AC in the summer?


  • Ironman
    Ironman Member Posts: 7,373
    You could use the white wire for that and loose the auxiliary heat, or they make modules that can create an additional wire.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • pecmsg
    pecmsg Member Posts: 4,837
    EBEBRATT-Ed Member Posts: 15,510
    Best way is to run another wire. Did he check the cable in the wall to be sure there are no spares? Whomever installed it should have run more wires at that time.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,818
    edited March 20
    What is on the other end of those wires?
    What does the air handler wiring look like?

    It is quite possible that you have only 5 conductors.
    18/2 is usually red and white
    13/3 is usually red white and green
    18/4 is usually red white green and yellow
    18/5 is usually red white green yellow and blue.
    Since that is the colors you have showing there is a possibility that you have one thermostat wire that has 5 conductors.

    You can check the other end of the wire at the air handler without messing with the thermostat at the wall. See if there are more wires like perhaps a brown or orange wire that will be incliuded in the more popular 18/7 or 18/8 wires for heat pump thermostats.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics