A/C not turning off when target Temp is reached

[101Media]

I just had my A/C unit replaced my nest thermostat remained as it was in perfect working condition. and because I live in Florida it is always set to cool. The issue I have is that the A/C normally would automatically shut down when the target temperature was reached, however, now the A/C unit will stay on all the time even when the temperature is actually much colder.  For example last night outside temperature was 59˚ and my target temperature was set to 79˚ which should normally keep the A/C unit off since it's already below the target temp. but the unit stayed on all night.  I could not find a way to fix this, so I either keep the A/C unit on 24/7 or shut it off via the breaker.  Thanks in advance.

[zoeuvre]

Hi 101Media, 

Uh-oh! I'm sorry to hear that your AC doesn't turn off even the thermostat reached the target temperature already. Kindly remove the thermostat display from the base and wait about five minutes and check if the system turns off or stays on.  

Let us know how it goes.

Best,

Zoe

[101Media]

Hello Zoeuvre, Thank you so much for responding. I did as you asked and removed the thermostat display from the base for about five minutes (a little over) and the system stays on.

[Jenelyn_O]

Hi there,

Chiming in — thanks for keeping us in the loop. I'd like to take a closer look at it. Could you please post a picture of the wires connected to your Nest Thermostat? Also, check your thermostat's Energy History. It will help you see what your thermostat is doing previously. 

I appreciate your input, Zoe.

Regards,

Jenelyn

[101Media]

Nest thermostat wiring

[Jenelyn_O]

Hey 101Media,

Thanks for sharing the photo of your Nest Learning thermostat wiring. You have a conventional system, and the wires responsible for your cooling are Y1, G, and RC. 

Let's sort this out: 

1. Shut down your HVAC system at the breaker box. Ensure as closely as possible that all power to the system is off before proceeding.
2. Remove your Y1 and G wire. 
   Important: Any removed wire should not touch any other wire, especially not a power wire. Leave the wire(s) sticking straight out and separated from any other wires before restoring power.
3. Leave the thermostat display off the base.
4. Turn the power back on.
5. Wait for a maximum of five minutes to see if your AC will still turn on and stay on with the display removed.

Please keep me posted.

All the best,

Jenelyn