AC doesn’t work with New Nest Thermostat

[Arizona_Boy]

I recently installed a brand new Nest Learning Thermostat to replace my old thermostat. Unfortunately, while my AC unit works perfectly with the old thermostat, the new Nest thermostat only blows warm air instead of cool air.

Here are the details of my setup:

• Wiring:
• G (green)
• C (blue)
• Y (yellow)
• W (white)
• Rh (red)
• I have followed the installation instructions meticulously and confirmed the wiring is correct.
• I have also set up the Nest thermostat in the app, and all tests for the fan, heat, and cooling indicated everything was functioning correctly.

Despite these steps, the AC only blows warm air when controlled by the Nest thermostat. This issue is quite frustrating, and I've had to revert to the old thermostat to get my AC cooling again.

Do you have any suggestions or ideas about what might be causing this issue?

Thanks for your help.

[luciaaa]

Hi, @Arizona_Boy,

Thank you for reaching out to the community. I'm truly sorry that your thermostat is blowing hot air instead of cooling. I'd be happy to help you troubleshoot further.

To better assist you, I have some questions about your thermostat:

• Is your heater source gas or electric?
• If possible, could you share a picture of your old wiring configuration and the current one?
• Do you see a power error code on your thermostat?
• What is the make and model of the cooling and heating system?

In the meantime, here are a few troubleshooting steps you can try:

Important: Before you begin, turn off the power breaker to your HVAC system.

1. Reseat the wires and ensure the button next to the terminal is pushed down.
2. Turn on the breakers.
3. Perform a factory reset on the thermostat.
4. Set up the thermostat.

Please let me know how it goes.

Best regards, 

Ana.

[Arizona_Boy]

 

Hi Ana,

Thank you for your prompt response and willingness to assist.

To answer your questions:

1. My heater source is electric.
2. I don't see any power error codes on my Nest thermostat.
3. I have already checked all the wire connections, reseated them, and ensured the button next to the terminal is pushed down.
4. I performed a factory reset on the thermostat and set it up again.

Despite these steps, the thermostat still blows hot air instead of cooling.

Thanks again for your help.

[luciaaa]

Hi, @Arizona_Boy,

I appreciate the time for replying to my previous post. Thank you so much for providing me with the information requested and for following the troubleshooting steps. I’m sorry that after following those steps the AC is still not turning on.

After checking the picture you provided, I’d like to know:

• Do you have a conventional or heat pump system?
• Did you remove the jumper that goes from Rc to Rh?
• Would you mind sharing a picture of your current wiring configuration?
• If you're comfortable doing so, would you mind sharing a picture of your control panel on your furnace?

Feel free to ask any questions you might have along the way.

Best regards, 

Ana

[Arizona_Boy]

Thank you for your message.

I have a conventional AC system, and I did remove the jumper between Rc and Rh as per the troubleshooting steps. Check my first message, you can find wire layouts.

I wanted to clarify that my cooling and heating systems are working perfectly with my old thermostat. The issue is that they don’t work with the Nest thermostat, which is why I am seeking some explanation from Nest regarding this problem.

Feel free to ask any questions you might have along the way.

Best regards,

[luciaaa]

Hi, @Arizona_Boy, 

Thank you so much for replying to my previous post and the information provided. I know how uncomfortable and inconvenient it is to be without AC. I'm here to help you get your system back up and running as quickly as possible.

Thank you so much for your understanding. As part of the troubleshooting process, I need a picture of your control board on your furnace so we can take a look at how this is set up, and this way the correct instructions can be provided to you. In case the steps don't work, then we can see any other available options.

Keep me posted.

Best regards,
Ana.