Hi everyone,
I recently purchased a Nest Learning Thermostat to replace the honeywell that is currently in place.
Current equipment: honeywell thermostat, Trane single-package heat pump: 4WHC4036A1000BA (no control panel).
History/Notes:
- I live in a townhouse in Arizona and have a single packaged unit on the roof.
- Current thermostat is wired Y to Y, W to W, R to R, and G to G. I can get cold or heat with the honeywell depending on if I have it set to heat or cool. Honeywell thermostat wiring
- When I installed the Nest, it had me connect R to Rh, Y to Y1, G to G, and W to W1. The Nest was able to charge when the wires were in this configuration, but no cold air came out of the vents when it was in cool mode.
- I start reading up about how I likely need a common wire. Behind the thermostat, there is an used blue wire, which appears to be the common wire. It's wrapped around the others.
- I try this configuration: R to Rh, Y to Y1, G to G, W to W1, and B (common wire) to C. In this setup, the Nest couldn't charge and would drain the battery. Also, no cold air.
- When I check the control box of the heat pump, it's difficult to tell, but it doesn't look like it has a control board. The thin wires are connected to thicker wires (see photo). I find (what I think are) the wires that I'm looking for. The blue wire isn't connected to the thick blue wire. On the heat pump side, it looks like it's wired G-G, Y-Y, R-R, W-O, B-nothing. Heat pump control box Wire connections - heat pump
- I try connecting the thin blue to the thick blue wire and cap them. The nest still can't charge in this configuration and no cool air.
Questions:
- Is it odd that the honeywell had been wired W-W, but on the heat pump it was W-O?
- Is it necessary to have a common wire? Mine only seems to charge when it's connected without one (though no cool air).
Final notes:
- Setting as I'm in AZ, I can't be without AC right now. So I put the old thermostat back on with the original wiring.
- I'm hoping to get some advice on how to wire this before I cave and hire an AC professional.
- I have all of the manuals for the equipment, so if any additional info is needed, please let me know.
Thanks in advance!
