installed Nest but won't blow A/C Cold air

[Clee1228]

Need help

I installed the nest but it's not blowing cold air just warm air, what I'm I missing? TIA

[mikev552]

please post a pic of how you wired the Nest and photo of the control board near blower motor to make sure the color of the wires match up to the thermostat. You also need to find out what that unused white wire is connected to, if anything. Please get a good look at the control board. Look for the matching letters from thermostat, Y C G W R....etc. The letter markers will be near screws.

[MrLou]

Yes, Mike is correct, need a photo of how the Nest is wired and a picture of your control board. Y terminal is what controls cooling and sends the signal to your outdoor condenser unit. If you just have warm ambient air coming out of the vents then the condenser must not be turning on outside, I would check that first. If condenser is on, then the issue lies with the condenser itself and not the thermostat.

[Clee1228]

pretty much I put the wires to same letter 

[mikev552]

A couple of things to check now. Make sure wires are inserted correctly and are making full contact. Confirm wire colors at the blower motor. Also, another important thing I noticed is that your C is not being used. This supplies constant power to Nest and it definitely should be used since the Nest needs to be connected to WiFi  and not have issues running your equipment....I saw you have an unused white wire. This can possibly be used as your C wire. But it all depends what is going on at the control board. also verify the yellow wire is going to the Y slot on the control board. This is for the AC. 

Again, take photo of the control board. It's the only way to see what's going on 

[Jake]

Hey all,

Sorry for the late reply. I wanted to check in and see if you are still in need of any help? Please let me know, as I would be happy to assist, and answer any questions you may have.

Best regards,
Jake

[Jake]

Hey all,

I wanted to check in and see if you are still in need of any help with your device? Please let me know, as I would be happy to assist, and answer any questions you may have.

Best regards,
Jake

[Jake]

Hey all,

I want to ensure you are good to go, and everything is working properly. Please let me know if you are still having trouble, as I will be locking the thread in 24 hours due to inactivity.

Best regards,
Jake

[NanaDuck]

Just installed new nest thermostat and set to cool and blowing warm air.  What to do?

[Ryan_G]

Hi NanaDuck,

Thanks for reaching out here in the Google Nest Community.

You could check this link on how to change the OB orientation if you're using a heat pump system. Let us know how it goes by replying to this thread.

Best regards

Ryan

[Jake]

Hey NanaDuck,

I wanted to check in and see if you managed to see Ryan's post. Please let me know if you have any questions from here. I would be happy to assist, and ensure you are good to go.

Best regards,
Jake

[Jake]

Hey NanaDuck,

I wanted to check back in, and ensure everything is working properly. Please let me know if you are still having trouble, as I will be locking the thread in 24 hours due to inactivity.

Best regards,
Jake

[mikev552]

 

check your wiring again. You should have something similar. I upgraded my wires to 5 and all the colors match. And blue being the C wire. 

[Patrick_Caezza]

Do you have a heat pump or a conventional system? If you are not sure, then take a look at the terminal block on the control board in the furnace/air handler. The fact that they used the gray(?) wire instead of the white wire makes me think you might have a heat pump. Post a picture of the terminal block here

While you are checking the terminal block, I would highly suggest that you use the extra blue wire I see and connect it to the C terminal on the control board.

Does the Nest thermostat have a cooling option displayed?

[CoolingWizard]

Heat pump systems need the O/B wire. Some heat pumps are O models and some are B models.  If you have an O model, the O/B wire is energized in cooling mode. If you have a B model, the O/B wire is energized in heating mode.  In your old Honeywell thermostat, the O/B wire was the W terminal and the thermostat was programmed to energize the O/B wire to get cooling.  It looks like you have an O model. Basically, The R wire brings 24 Volts AC power to the thermostat.  The Y terminal is for a call for cooling.  The W terminal is a call for Heat. The G terminal if for turning on the Blower Fan.  The C terminal is the Common return for the 24VAC. The O/B wire is for changing the 4-way reversing valve in a heat pump.  Your Honeywell thermostat used Y terminal to turn on the compressor.  For you, move the W wire to the O/B on your Nest.  You will need to run a system test. If it blows warm when in cooling mode, or cool when in heating mode, you need to change the O/B function. Open the nest app and select the thermostat, tap the configuration icon, select heat pump, if it is set to O change it to B, if it is B change it to O.  Run the system test again.