Nest not turning on Condenser, not cooling

[Kelli]

we have figured out after a few hot days that our house isn’t cooling and the condenser is not turning on when we turn the AC on, no matter the temp or time of day.

Pics of previous set up and nest set up.

help!

 

 

[Patrick_Caezza · Accepted solution]

When you replaced the wireless device did you run a new thermostat cable?

Unless you have a unique system it looks like you are missing the cable that goes to the outside unit. It is a two-wire cable that is connected to the Y and C terminals. Without it, the compressor that is located outside can never turn on.

[nlambright]

Thank you for posting this.  I'm setting up Nest thermostat for the 1st time in our house with the same issue. Will post a solution if I can find one

[PeteMagoni]

You probably have a bad capacitor on your air conditioning unit. All air conditioners have a capacitor start if the capacitor is bad the condenser won't turn on. 

[Kelli]

Even if it worked perfectly fine the day before we switched to the nest?

but I’ll still look into checking that.

[nlambright]

From the research on my scenario, I need to get a power connector (my condenser & entire system works fine with the previous thermostat).  If the condenser stops working after no previous problem, it can be low battery in the Nest thermostat, or it could be the capacitor.  If you still have the old thermostat, reconnect it.  If it works, that will provide the answer

[Patrick_Caezza]

Do you have a conventional system or a heat pump?

Post a picture of the terminal block on the control board in the furnace/air handler.

[Kelli]

Here is the picture;

[Patrick_Caezza · Accepted solution]

When you replaced the wireless device did you run a new thermostat cable?

Unless you have a unique system it looks like you are missing the cable that goes to the outside unit. It is a two-wire cable that is connected to the Y and C terminals. Without it, the compressor that is located outside can never turn on.

[Kelli]

Thank you for your help. I was able to rewire the correct wires into the Y and C ports and now everything works as it should. 

 

[Patrick_Caezza]

Perfect

[MelbaDT]

Hey folks, 

Thanks for taking care of this, Patrick_Caezza. 

Kelli, thanks for keeping us in the loop and we're glad to hear that you've got a working thermostat by following Patrick's suggestions. Hats off to both of you!

nlambright, how about your thermostat? Still need help with it?

Best, 

Melba

[nlambright · Accepted solution]

Melba, thank you for checking back with me.  After further research we determined that there was never C connected at the heat pump board.  After making the C connection to the spare wire in the cable, it worked great

[MelbaDT]

Hi nlambright, 

Awesome — glad to hear that you're sorted it out as well and now, you've got a working thermostat. Feel free to let us know if anything comes up. 

Cheers, 

Melba

[MelbaDT]

Hi, 

We haven't heard from you in a while so we'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