Wires aren't detected (and they are connected ) - Furnace HAS a C wire

[NeighborNext2U]

2023: August 31

Error

It tells me that the Y C G are not detected by red lettering on the app's wire configuration screen.

I know all 5 wires are clean, proper gauge, correctly hooked up to furnace. I have restripped each, they are straight and the thumb button is staying depressed.

Furnace interior Boardclip, strip, clean, straight, tabs stay pressedjunction box at furnaceyellow showing good guage & single pc copper

***yellow pulled to show you intergrity of wire (clean, stripped, correct guage, straight); i put it back in.

I've turned the furnace breaker off, waited 5minutes+, turned it back on and re-attempted the setup thru Google Home app, for notification that the Y(cooling/yellow) C (common/blue) G (fan/green) are not connected -so no luck, I have restarted AND performed a factory reset. I have replaced the alkaline AAA batteries in the unit (battery says good). I have ensured software is most up to date/ V 1.3-10

Any help would be appreciated, perhaps a new unit (would you send me a replacement)? As I have the same model unit working on the other side of the house on the same type of furnace, same wire configuration and it works.

Thanks,

Neighbor

[CoolingWizard]

@NeighborNext2U ,

Notice how the tabs if the wire that are detected stay further down? Make sure the copper wire goes in far enough to reach the back. If the tab comes up half way, it not in far enough to be detected.  

AC Cooling Wizard

[NeighborNext2U]

The photo is misleading, they are all depressed similarly. To be thorough, I pulled all wires and re- inserted. Did not fix it

[NeighborNext2U]

Anybody got any other ideas, would like to try a new base plate that holds the wires - Nest? Canyou provide?

[NeighborNext2U]

I've obtained a  'google nest power connector' - how shall I connect this while having an entact C-wire on my furnace? See photos of my furnace wiring in the initial thread.

[CoolingWizard]

Do you have a Volt Ohm Multimeter?  You need to check the alternating current voltage between you R wire and your C wire at the thermostat.  Verify that there is 24Voltas AC power +/- 5VAC.  If there is AC power present, the problem will be in the Nest Backplate. If there is less than 20VAC there is not enough voltage.  In all likelihood you have a bad backplate.

AC Cooling Wizard

[NeighborNext2U]

New back plate did not help. Never used the Nest Power Connector. Only voltage (~28) I have is between R (power) and W (heat). Zero or low fluttery for all others (YGC). Further tests by HVAC pro indicated I have a bad "brown" wire in the wall. In that the brown wire which holds the RWYGC has a bad YGC -maybe crimped within the wall or not functional for whatever reason.

Went back to two wire 2012 Bryant thermostat. Chose not to proceed with expensive re-wiring within wall and ceiling back to furnace.

Q: what options might I have moving forward in the next decade when the wish list is wi-fi remote control without a YGC wire.  RFD thermostat i understand would need to be manually reset in the event of a power outage (which I have frequently). Which does me no good when I'm away on travel.

[CoolingWizard]

@NeighborNext2U ,

how far apart is the thermostat and the Air Handler? Often the low voltage thermostat cable is not stapled to a stud. You need to go into the attic and find the brown cable.  Push 1 foot of it into the wall. The. Go to the thermostat and see if you can pull that extra foot out of the wall.  Report if you were able to do this. 

AC Cooling Wizard

[NeighborNext2U]

Unfortunately, the run is a floor and three rooms away. It runs from the basement along a ceiling and up into the wall where the thermostat resides. We did pull and jiggle the brown wire (from both ends at the furnace and at the hole in the wall) thinking perhaps it was pinched but that failed to resolve the issue. We were unable to "pull" much as we suspect the wire was stapled along the run.

[Bonnybrtt]

I'm having the exact same problem. Any luck?