Nest 3rd Gen thermostat - not turing on the A/C

[PaulMontreal]

Hi all,

Bought  a new house and inherited their Nest 3rg Gen thermostat.  I had a nest 2nd gen in my previous house and had no issues.

When I turn the control to Cool and set the temperature to below current reading , the heat pump does turn on but is blowing hot air in stead of cold.  Had an heat pump tech out to take a look and the unit is works properly. 

The tech seems to think that the "OB" wire connection in the thermostat not sending the correct signal to the thermal  pump to turn the AC - added a "jumper" wire and now it's working when "cool" kicks in.

Is there a warranty on the thermostat ?

Thanks 

Paul in Montreal Canada.

[CoolingWizard]

@PaulMontreal , There is nothing wrong with your thermostat. It simply was not installed and configured properly.  The Heat pump is either an O model or an B model. B models are by default air conditioners and O models are by default Heaters.  So, you can configure the OB  mode to set the type.  On your nest display go to SETTINGS > EQUIPMENT > CONTINUE > CONTINUE > HEAT PUMP.  You will see a check mark in front of O or B.  Whichever yours is currently set to, just select the other.  Now you must ensure your Oil Furnace control wire is placed in W1 and not W2/AUX.  Then you will need to go to SETTINGS > PRO SETUP > CONTINUE.  Here you will see a picture display of the backplate and the wires that are detected.  You will see a green wedge if the Nest knows the function of an attached wire.  If a wedge is yellow, you need to select it and define the function.  Make sure you set your heat type as duel fuel. And then set the temperature at witch you want the heat pump to stop and the oil burner to take over.  I hope that this helps to clarify the heat pump operation. Also the “jumper wire” the tech installed must be removed.  Keep in mind that the Nest backplate is not designed to have multiple wires in a single connection point.  If two wires are forced in it will damage the backplate.  

AC Cooling Wizard

[PaulMontreal]

thank you very much for the quick reply.  I'll try that tomorrow and let you know. 

[Jenelyn_O]

Hi there,

Thanks for reaching out. How's your Nest Learning Thermostat? Were you able to try the steps provided above? Please keep us posted.

I appreciate your help, @CoolingWizard.

Best,

Jenelyn

[Jenelyn_O]

Hi PaulMontreal,

Checking if you still need help. Please let me know, as I'll be willing to assist you further. 

Thanks,

Jenelyn

[Jenelyn_O]

Hey PaulMontreal,

We haven't heard from you in a while so we'll be locking this thread if there is no update within 24 hours. If you need assistance or want to discuss topics, feel free to start a new thread.

Regards,

Jenelyn