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Wiring clarification with Nest Power Connector

AirBreezy
Community Member

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.

6 REPLIES 6

Houptee
Silver Product Expert
Silver Product Expert

This video might help.

https://youtu.be/xlx2Um6D1Z8


Houptee -- NJ Master HVAC Licensed Contractor

EdwardT
Community Specialist
Community Specialist

Hi folks,

 

@Houptee, thanks for the help!

 

@AirBreezy, how's it going with your Nest Thermostat? Were you able to check the link that Houptee provided? Let us know if you have questions and we'd be glad to assist you.

 

Thanks,

Edward

AirBreezy
Community Member

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.

EdwardT
Community Specialist
Community Specialist

Hi AirBreezy,

 

Thanks for the response. We'd like to know more about this. Please fill out this form so we could investigate further.

 

Thanks,

Edward

EdwardT
Community Specialist
Community Specialist

Hey AirBreezy,

 

I'm checking back in. Were you able to fill out the form? Let us know if you have questions and we'd be glad to assist.

 

Thanks,

Edward

EdwardT
Community Specialist
Community Specialist

Hi AirBreezy,

 

I'm just checking in to make sure that you've seen our response. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.

 

Thanks,

Edward