Hello, wondering if anyone could briefly explain why the W-wire worked instead of the Y-wire when I was installing the nest power connector following the heating and cooling instructions (instructions called for using the Y-wire). I have a gas furnace with a Y-G-W-R-C connector, 4-wire cable from tstat to furnace (no C-wire) and an AC compressor/outdoor condensing unit.
I initially followed the power connector instructions for a heating & cooling system, connecting the power connector Y-R-C white wires to the furnace and the Y-R gray wires to the tstat side using the wire connectors provided. I made sure everything was snug and the wiring matching the instructions. The power connector was detected and I tried to enable heating but the fan and burner won't come on. I tried to enable cooling and only the AC compressor/condenser comes on.
I then removed the power connector, reinstated the furnace wiring to the original positions, and this time I followed the heating only instructions, connecting the power connector W-R-C white wires to the furnace and the W-R gray wires to the tstat side. The power connector was detected and the furnace/fan actually came on when I enabled heating, and the AC compressor + furnace blower came on when I enabled cooling.
Why would the W-wire work but the Y-wire didn't, despite following instructions? just curious to know - maybe somehow the Y-wire wasn't able to energize the furnace heating and blower circuit.
The nest thermostat and power connector is working but the video link does not answer the question exactly. At 3:42 of the video, the directions says to wire the power connector to Y wire for a cooling and heating system. Tried that but the furnace and blower wouldn't come on in heating mode, and only my AC compressor/condenser came on in cooling mode. I then tried wiring the power connector to W wire instead, and everything works accordingly in both heating and cooling mode. Wondering why it worked for the W wire and not the Y wire.
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