Heat Pump with Nest

[Mark_13]

Hello - I have a Trane heatpump system (13 years old). Whenever the thermostat turns the auxiliary heat (or even just running the fan) option on due to low temperatures, there seems to be a signal being sent to the heatpump and it makes a loud ticking sound. Is something not wired correctly in the thermostat? this never used to happen with the old thermostat. it just seems like a signal is being sent to the heatpump and it shouldn't be happening. Please advise any assistance you can

[CoolingWizard]

Trane heat pumps have a Y2 signal wire to the indoor air handler.  If the HVAC installation company cross wired the Y2 in the air handler to the O/B wire you are hearing the Defrost Control Board activating the condenser fan lockout relay. What is the manufacturer model number of the outdoor unit and the indoor unit?

Ken, The AC Cooling Wizard

[Jenelyn_O]

Hi there,

Thanks for posting in the Google Nest Community forum. Could you please share with us the information asked by CoolingWizard? It will help us to move forward. 

I appreciate your help, @CoolingWizard.

Best,

Jenelyn

[Jenelyn_O]

Hi Mark_13,

I wanted to follow up if you still need help. Please let me know if you’re still having any concerns or questions from here, as I would be happy to take a closer look and assist you further.

Thanks,

Jenelyn

[Jenelyn_O]

Hello Mark_13,

I'm just checking in to make sure that you've seen our response. Please let us know if you have any other questions or concerns, as I'll be locking this thread in 24 hours.

Regards,

Jenelyn