cooling option no longer available

[Rubacu]

Hello, I have an existing Nest learning thermostat installed back in March. Everything worked just fine, however now I don’t have a cooling option available to use. 

Nothing has changed as far as equipment or wiring. What is going on?

[aperezdeleon]

Hi there Rubacu,

Thanks for reaching out to our community.

It sure can be frustrating when your Nest learning thermostat used to show cooling options, but now it doesn't. Let's see what we can do to fix it.

My first suggestion is to check the wires on the base. Turn off the power first, then remove the wires from your thermostat and make sure they're not loose or corroded. This can interrupt the signal between the Nest thermostat and your HVAC system. Make sure all the connector buttons are pressed down firmly.

Also, verify that your AC is getting power and that no switches have been accidentally turned off.

If you're not comfortable checking the wires yourself, it's best to consult an HVAC technician.

Let me know how it goes.

Regards,
Angel.

[Rubacu]

Hello, 

I have tried all of the above recommendations. It still won’t give me a cooling option. 

I installed this thermostat back in December and it was working fine with the wiring just as it is now and the same equipment. I’m thinking this has to be a software issue, I can’t explain it any other way.

Thank you.

[Needmilk45boys]

Did you ever find an answer? My unit has flipped to heat from cooling 2-3 times and now I don’t even have a cooling option on the thermostat!

[Rubacu]

No answer yet, still working on it with more information provided. I’ll let you know if anything works.

[aperezdeleon]

Hello folks,

Thanks for getting back to me.

As you mentioned completing the tests I requested, would it be possible to share a picture of your current wiring configuration? I'd appreciate knowing your current wiring configuration and, if possible, a picture of the wiring that comes directly from your system. This would help me understand the reason your thermostat lost the cooling option.

Let me know how it goes.

Regards,
Angel.

[Rubacu]

Hello Angel, 

Thanks for getting back to me. Let me paint the picture:

I leave in a condo that has an air handler unit in the ceiling in my unit and a condenser on the roof. Unit was installed at the end of 2019 and has always been wired the same way.

The thermostat wire connecting the equipment to the thermostat only has 4 wires, as you can see in the pictures the unit label has the same for wires connecting to the thermostat. White, Green, Red, and Purple (which is actually Blue)

The Air handler has two power wires coming out of it, one goes to the Red wire on the Air handler motor, and the other goes to the Red wire on the thermostat.

There is a wire coming from the roof top condenser that has 4 wires in it, White, Green, Yellow, and Red.

The Red wire is connected to the Blue on the thermostat.

The White is connected to the Purple on the Air handler motor.

The other two wires were cut short and have never been connected.

I hope this helps you and thank you again for your time!

[aperezdeleon]

Hi there Rubacu,
 
Thanks for getting back to me.
 
Whether your thermostat can control cooling depends entirely on the wires it detects. These wires will be different depending on what system your thermostat is connected to.
 
With your current wire configuration, your Nest thermostat should detect a conventional forced air system. Since you don't have a Y1 wire attached to the baseplate, your thermostat can't have a cooling mode, as the Y1 wire is used for cooling activation.
 
Your system might work with cooling if it were a heat pump. However, looking at the wiring diagram, your unit is a conventional system, so you'll need to get a Y1 wire out of your AC.
 
I suggest getting in touch with one of our recommended technicians to check if installing a Y1 wire is possible since you've told me your system is capable of cooling.
 
Let me know how it goes.
 
Regards,
Angel.

[Rubacu]

Hello, 

As I said before the thermostat used to work with the same equipment and wiring. I replaced the Nest Learning thermostat with a $29.00 Honeywell with a 4 wire configuration and now the system works again. 

Thank you.