Nest not working with Trane system

[fourharts56]

I have a new Trane Heat pump system that was installed in May 2023. I installed a Nest Learning thermostat in JUL23, unfortunately I did not test the heat in July. When the heat needed to be turned on it did not work. It did work all summer with A/C.

Trane system is: A4AH4E24A1B60A

I will attach photos of what I did. 

[fourharts56]

Apparently I don't have permission to post photos.

[zoeuvre]

Hi fourharts56, 

Thanks for posting here in the Community forum and for showing interest in our Nest Thermostats. You could link the photo of your current thermostat wiring configuration via Google Photos so we can take a closer look. You may also check the compatibility of your Trane Heat pump system with our Nest Thermostat using our Compatibility Checker.

Keep us posted. We're happy to help.

Best,

Zoe 

[fourharts56]

[fourharts56]

So the first photo is of original thermostat. Second photo was how I wired for the Trane system. A/C worked fine but heat never worked.

[zoeuvre]

Hi there, 

Thanks for getting back to us. I checked your wires, and I can confirm that you wired them correctly to your Nest Learning Thermostat base. To check more on why it does not come out after installing the Nest Learning Thermostat, a few questions:

• Does the thermostat screen indicate that it’s actively calling for heating?
• What type of furnace do you have? (gas, electric, etc.)
• When did heating last work?
• Did heating ever work with the Nest thermostat? If not, did the heating work with the previous thermostat?
• Did you turn off the power to the HVAC system?
  • Did you recently turn off any breakers?
  • Have you recently experienced a brownout or blackout?
  • Is there a light switch near the heater that controls an outlet?
• Did you select the correct fuel type?
• Do the LED lights blink on the HVAC control board? If yes, locate the light.
• When was the last time you changed the furnace's air filter?
• Have you experienced extremely cold weather lately?
• Is this the first notable temperature drop of the year in the area?

I'll look forward to your response. 

Thanks,

Zoe

[fourharts56]

Background: it is a new Trane Heat pump system, system number posted above. installed in May 2023 by previous owner, I bought house in JUN23 everything worked fine as far as I knew. I installed nest thermostat in JUL 23. A/C worked fine, at the time in JUL I thought when I test heat that it worked but it did not. I had a HVAC technician come out for winter light off on system since it is part of my package I pay for. Heat was turned on and it did not work with nest thermostat. I placed old thermostat back on and it worked fine in both A/C and Heat. I'm an engineer by trade, I know how to turn off and on breakers, I also know about the light switch which this unit does not have. (My downstairs Furnace system does have the light switch).

With Nest thermostat installed and Heat on it indicates it is running with heat on but air that blows out is just room temperature. Equipment was programmed for heat pump with aux heat backup. There is no HVAC control panel visible to look for lights on the attic unit although I have not removed the access cover.

I have noticed some other threads that have strange recommendations for wiring a Trane system such a

Red - R to Rc

 Orange - O to OB

Green - G to G

Yellow - Y to Y1

Black - X2 - * (set for emergency heat)(jumper to U not needed)

Blue - W to W2

is this still accurate?

[fourharts56]

This last photo came with installation manual. top left is the heat pump installation color code.

[fourharts56]

Help from anyone please!

Before I put my Nest thermostat back on the wall and "try to figure it out" was looking for guidance.

Thank you zoeuvre for the help so far.

[fourharts56]

Does anyone have a recommendation? I would take them back but Lowe’s said they would not take them. I really like the nest features but unless I can get a good recommendation on how to wire they will stay on the shelve. 

[zoeuvre]

Hello fourharts56,

I'm sorry for the late reply. The wiring configuration you provided for a Trane system with a Nest Learning Thermostat is generally accurate, but it's important to note that wiring configurations can vary depending on the specific model and setup of your HVAC system. While the general wiring conventions are often consistent, it's always best to refer to the specific wiring diagrams and instructions provided by Trane and Nest for your particular equipment. That being said, here is a typical wiring configuration for a Trane heat pump system with a Nest Learning Thermostat:

• Red wire (R) to Rc (power)
• Orange wire (O) to O/B (reversing valve)
• Green wire (G) to G (fan)
• Yellow wire (Y) to Y1 (compressor)
• Blue wire (W) to W2/Aux (auxiliary heat)
• Black wire (X2) is not typically used for a heat pump system

If you are experiencing issues with the heat function when using the Nest Learning Thermostat, it's recommended to double-check the wiring configuration, ensure that the thermostat settings are correctly configured for a heat pump system. Also, could you answer the questions I asked above so I can take a closer look? 

Regards,

Zoe

[fourharts56]

Thanks for the reply. Answers below as best I can. Also I don't have a black wire only white.

• Does the thermostat screen indicate that it’s actively calling for heating? Yes it indicates HEAT
• What type of furnace do you have? (gas, electric, etc.) This is a Heat Pump only.
• When did heating last work? Worked with old thermostat and again with old thermostat when I removed the Nest.
• Did heating ever work with the Nest thermostat? If not, did the heating work with the previous thermostat? No it did not.
• Did you turn off the power to the HVAC system? Yes, turned off unit at thermostat then tripped everything at the breaker, verified thermostat deenergized then removed old thermostat and installed Nest
  • Did you recently turn off any breakers? Just to install thermostats
  • Have you recently experienced a brownout or blackout? not recently but it has gone off during the 4 months the thermostats were installed
  • Is there a light switch near the heater that controls an outlet? No not on this unit. On my other one yes.
• Did you select the correct fuel type? Yes. Heat Pump
• Do the LED lights blink on the HVAC control board? If yes, locate the light. Not sure what board you are talking about? Are you talking about on the unit in the attic? it is inclosed and I have not opened it up to look.
• When was the last time you changed the furnace's air filter? every 3 months
• Have you experienced extremely cold weather lately? N/A old thermostat is installed, have not put Nest back in until I have a solid plan.
• Is this the first notable temperature drop of the year in the area? N/A same as above.

Thank you for your time.