Any HVAC guys around? Stupid “c” wire question for google nest

[Raycaster]

Doing a simple nest thermostat upgrade for a friend and he assumed there was no common wire. He ordered the Nest power adapter and I went over to install.

Didnt have much time but after looking at his current setup it looked like it had the blue c wire but it was connected the aux of the original thermostat.

I installed the nest and used the blue as the common. I have included images. I had to run quickly but doing a quick setup everything looked good but I think I got a c wire missing message. 
 

Anyways everything running but will go back (with more time) to install the nest power adapter if in fact the blue wire isnt common.

 

Any help appreciated. 

[BillM]

Did you check the furnace circuit board to see if there's anything connected to C?   First thing you really should do.  

[Raycaster]

Bill, thank you for the reply.

Will check for sure when I get there, thanks.

[Terry]

C is the common wire isn’t it 

do you have 24 volts somewhere 

[AlmaMatter]

Just wanna add that you might consider taking a multimeter and checking for 24 volts between the R and C terminals to confirm the blue wire is, in fact, a common wire. If not, then installing the Nest power adapter as you initially planned would be the right way to go. But if you're not 100% confident or run into other issues, sometimes it's best to bring in the pros. Companies that specialize in AC repair like ac repair in Riverview, FL are well-versed in HVAC systems and smart thermostat installations. They can provide expert services that go beyond just a quick fix, ensuring that everything is set up properly and functioning efficiently.

Edited November 9, 2023 by AlmaMatter

[Terry]

I would think he got the problem solved many months ago