Thermostat wiring HELP

[28Eliminator]

Putting a new WiFi thermostat in. Cooling works fine, but no heat. The old thermostat was battery powered. The new one is not, so I have to pull 24v from the FAU. Here is a pic of the wiring of the old thermostat.

Here’s what I have on the new one. I hooked up the blue wire (common) for 24v. But I’m not sure where to hook it up in the FAU?? (Second pic)

Help... it’s chilly in here [emoji16]


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[Rbcconst]

Lmao not much help but all I do know is if you accidentally touch a few of the wires together it blows the 3 amp fuse on the fau circuit board and then nothing works for shit!


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[28Eliminator]

Lmao not much help but all I do know is if you accidentally touch a few of the wires together it blows the 3 amp fuse on the fau circuit board and then nothing works for shit!


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I don’t think I blew anything up... yet [emoji16]


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[THE WIDGE]

I had carey’s Come out and do mine in havi. My dumbass tried changing in 115 heat. I know he had to mess with a wire, I think the c wire up on the ac/ heater. Pain in the ass

 

[bocco]

Can you check with a volt meter to find the 24V terminal? My first guess would be to check the two terminals in the right that have a red and white wire coming from a separate bundle. Also I'm pretty sure you should set your volt meter to measure AC voltage.

 

[lbhsbz]

Can you check with a volt meter to find the 24V terminal? My first guess would be to check the two terminals in the right that have a red and white wire coming from a separate bundle. Also I'm pretty sure you should set your volt meter to measure AC voltage.

24V leg should be DC....no?

 

[wet hull]

Wires look right. I had to program mine first to get the heat to work. It needed to know all the components you have. That was honeywell. Switched to nest and much easier.

 

[28Eliminator]

Can you check with a volt meter to find the 24V terminal? My first guess would be to check the two terminals in the right that have a red and white wire coming from a separate bundle. Also I'm pretty sure you should set your volt meter to measure AC voltage.

I think I got it.. on the right of the pic, there’s a terminal B/C. I googled it, and it says that’s the common terminal for Trane systems.. heat is running... now to see if the cool still works


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[bocco]

24V leg should be DC....no?

I'm pretty sure it's AC since the XFMR steps down the 120V AC and there is no rectifier circuit to convert to DC.

 

[bocco]

I think this is it here. The red and white bundled wire comes from the XFMR.

 

[Riverbound]

Put the blue wire to the b/c terminal. And leave that red wire that’s in there as well. That’s your “c” for the condenser.


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[28Eliminator]

I think this is it here. The red and white bundled wire comes from the XFMR.

This is right... Trane units don’t specifically say “C”.. it’s “B/C”


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[gmnhra]

It is the Rojo B/C terminal.. some things get lost in translation