Air conditioning thermostat wiring help

Question

Really need some help. I was working on the wiring of my home air conditioning and managed to mess up the low voltage wiring.  I was installing a wifi thermostat and opened the panel to add a blue wire.  Discovered a lot of corrosion on the terminals.  I took a picture and proceeded to clean each terminal.  Well long story short.  My photo wasn't clear enough for me to get all the wires back where they belong.

I'm pretty sure I got the thermostat wires correct, what has me baffled is the low voltage wires to run the outside compressor.  My thermostat has power, the fan has power,  but I can't get the compressor outside to run.

I did some testing, and got the compressor fan to turn on, but it's not making cold air.  So I undid the wires.

Question is.  I have two low voltage wires that go to my outside compressor.  What should the connect to on my terminal panel.

I've attachéd a photo.  Notice the two wires on the side to my compressor.  It's a trane that's at least 10 years old.  It's a electric furnace and single stage ac, in south Florida.

Thank you.

user76730 · Answer

I am guessing B is common in your case. In that case Y and B.

I have drawn a line though the terminsals you will not be using since you have straight cooling and are using the air handler like an electric furnace.  R goes from the thermostat to the air handler but not the condensing unit as does W1 which is your heat strip. O is not used since you do not have a reversing valve. Y goes from the thermostat to the air handler then carries on to the condensing unit.  Note the common 24 volt is labeled B or B/C (this is typical with Trane products).  The B is likely labeled C on your wifi thermostat.  So C from the thermostat goes to B on the air handler and then on to the condensing unit. It does not matter which wire from the condensing unit goes to B or Y. I hope this edit clears up any confusion.

Air conditioning thermostat wiring help

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