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Best thermostat

Preuss
Community Member

My thermostat shows that the air is on, but it will not turn my ac on at all. I have changed the batteries, I have double checked the wiring, and I have even done a reset…it still won’t turn my air on.  What am I missing? 

6 REPLIES 6

MZellmer
Community Member

A number of things come to my mind with this situation:

  1. Not sure where you're located and what the outside temperatures are, but a few weeks ago when it was in the 30s here in WI, we couldn't get the AC started probably because the Nest knows what the outside temperature is thru the internet, and won't actually run the AC until the outside temperature is >40.
  2. Though a completely different system (a 2 zone system) on our old thermostat there was a mechanical switch to change from Heating to Cooling.  That switch had a lead (blue wire labeled O on our original thermostat) to the furnace control system that flipped a relay there to change from heating to cooling.  It appeared that the Nest Learning Thermostat did not have the capability of controlling that relay using the O/B lead. Any wire on the O/B terminal makes the Nest think you have a heat pump. In my post you can see I put an auxiliary switch at the furnace to control that relay manually rather than through the Nest.

 Maybe this helps, maybe not, but a couple of thoughts.

Probably should also be sure the power is on the to cooling system.  We have an outsider shutoff for the compressor that could keep the system from running, yet might show that cooling is on at the thermostat.

Patrick_Caezza
Platinum Product Expert
Platinum Product Expert

Post a picture of the original thermostat's wiring here


To ensure that I see your reply, please tag me using @Patrick_Caezza

MelbaDT
Community Specialist
Community Specialist

Hey folks, 

 

Appreciate your responses here, Patrick_Caezza and MZellmer. 

 

Preuss, I'm chiming in to check if everything is good here. If you still need help, please provide the photo being requested above so we could take a closer look at it. 

 

Best, 

Melba

MelbaDT
Community Specialist
Community Specialist

Hey Preuss, 

 

Checking back in — how's your thermostat now?

 

Best, 

Melba

MelbaDT
Community Specialist
Community Specialist

Hi, 

 

I haven't heard from you in a while so I'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community.

 

Best, 

Melba