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Brian HVAC Guy
Brian HVAC Guy, HVAC Technician
Category: HVAC
Satisfied Customers: 953
Experience:  I have been an HVAC/R mechanic/technician for 30+ years.
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My name is ***** ***** I have a specific question regarding

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Customer: My name is ***** ***** Kim I have a specific question regarding unusual wiring of my honeywell system. I have a C wire that is Blue connected to the B terminal as is the case for some honeywell systems. The issue I have is the installer used a standard 5 wire cable for the R, W, Y, B, G but I have a second cable running with it that has an extra white connected to either the W or O (for heat pump) and to the X2 I took a picture of the wiring before taking apart the old one but I seem to have confused which white wire connects to the W and O I am able to power everything on but when I turn on the heat, only cold air comes out so I'm wondering if this happens if I accidently switched the white wires and put the one that should be in W for O and vice versa.
JA: Thanks. Can you give me any more details about your issue?
Customer: what happens when i reverse the white wire for W with the white wire for O (heat pump)
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Submitted: 1 year ago.
Category: HVAC
Expert:  Brian HVAC Guy replied 1 year ago.

Hi I'm Brian and I'm here to help! So if i understand correctly, one of the whites was connected to O and the other one was connected to W and X2 is that correct?



Expert:  Brian HVAC Guy replied 1 year ago.

To answer your question simply, if they were previously connected to O and W/X2, there is no risk of damage if they are reversed but you will experience the symptoms you have if they are indeed reversed from the way they should be. If the other wire were connected to their corresponding terminals on a Trane heat pump thermostat, this is how you should wire your new one:

*Red to R (leave jumper to Rc)

*Blue to C (if your new Honeywell has a C terminal, otherwise tape it up and tuck it back in the wall)

*Yellow to Y

*Green to G

*One White to W/Aux/E (if Aux and E are separate terminals on your new Honeywell thermostat (some Honeywell's are like that) then you should install a small jumper wire between Aux and E.

*Second White to O/B

Since you don't remember which white went to which terminal, you just have to try it and see if the system works right. HOWEVER, there's a step you have to complete in the thermostat's installer setup program as stated in your manual first. You MUST tell the thermostat what type of heating/cooling system you have. So you would enter installer setup and under type of system, you should select "Heat Pump With Auxiliary Electric Heat" (or just HP with Aux heat). Depending on what model thermostat you bought, there may be another setting for what type of backup auxiliary heat you have so scroll through the instructions and if so, choose electric heat for the type of backup or auxiliary heat.

Then and only then can you make sure the two white wires are hooked up right or wrong. If wrong, it will heat in cool and cool in heat. Just switch them and you should be fine!

Let me know if you have further questions on this subject. Otherwise, please remember to rate before leaving (3 stars or higher please!). Bonuses are always appreciated! Thanks for allowing me to help and thanks for using Just Answer!

Thank you,