topic Re: Heat blows when AC is selected. in Nest Thermostats

Heat blows when AC is selected.

McAwesome — Sun, 12 Feb 2023 14:33:20 GMT

I have a heat pump, the heat works fine. When I select AC it still blows heat. Here is a picture of the original wiring and the nest wiring. I put all the same wires from the original unit to match up to what was on the nest.

Re: Heat blows when AC is selected.

Jenelyn_O — Sun, 12 Feb 2023 16:38:19 GMT

Hi McAwesome,

Thanks for reaching out and for providing those photos— I'd love to help.

We can use the labels below on your old thermostat as our reference for your heat pump. Please remove the orange wire on the Nest W1 terminal and move it to the OB Nest terminal. The OB terminal will serve for your heat pump wire. Note: Make sure to turn the breaker off before touching the wires. The rest of your wires are on the correct terminal.

Let me know how it goes.

Best,

Jenelyn

Re: Heat blows when AC is selected.

CoolingWizard — Sun, 12 Feb 2023 19:00:38 GMT

McAwsome,

Please allow me to add some information to increase your system knowledge.

You have a heat pump and when it comes to heat pumps, the compressor is energized and runs in both heating and cooling mode. What makes the heat pump work is there’s an internal reversing valve that is energized to switch it from heating to cooling or from cooling to heating. What the RV changes is the directional flow of the refrigerant. In your case your reversing valve is plumbed in such a way that by default you are a heating system. This is what’s known as a B model. The systems that by default are AC cooling models. They are called O models.

The yellow wire is what turns on the compressor and when you want to change from heating to cooling, you will need to have your thermostat energize the O/B wire. This is why @Jenelyn_O has advised you to move the wire that’s currently in W1 and re-inserted into the connector O/B.

I hope this helps you understand your Heat Pump better.

AC Cooling Wizard

Re: Heat blows when AC is selected.

McAwesome — Tue, 14 Feb 2023 02:27:04 GMT

Thanks so much for y’all’s help. Took 15seconds to move the wire and everything works like it’s supposed to! Again, thanks for taking the time to help me out!

Re: Heat blows when AC is selected.

Jeran — Wed, 15 Feb 2023 23:15:44 GMT

Thank you for helping out on this thread, Jenelyn and CoolingWizard!

Hey there McAwesome,

I'm just checking up on this thread, and I'm glad you were able to get everything wired properly! In that case, do you have any more questions or need any additional help? If not, I'll go ahead and lock this thread within 24 hours.

Best regards,
Jeran

Re: Heat blows when AC is selected.

McAwesome — Thu, 16 Feb 2023 03:14:07 GMT

Feel free to lock the thread. Again I appreciate the help solving my issue.

Re: Heat blows when AC is selected.

Markjosephp — Thu, 16 Feb 2023 14:57:49 GMT

Hello McAwesome,

We're happy to help! Thanks for your effort as well. So it looks like we can consider this one complete, and I will lock the thread in 24 hours unless I can help out with anything else.

Regards,

Mark