Connecti h wire

[Jd11420]

Trying to upgrade an old thermostat to nest, I have the following wires, yellow, white,  red and blue.. in many videos he 4th wire is green.. I'm confused as to where this blue wire goes..

[Jd11420]

Correction, I have the green wire but don't have the yellow

[johnCNA]

Are the terminals on the old thermostat not labelled?  Usually you just have to match the old letters to the Nest letters.

[Patrick_Caezza]

Post a picture of the original thermostat's wiring here

[Ryan_G]

Hey Richardrp,

I just wanted to follow up and see if you're still in need of help? Please let me know, as I would be happy to answer any questions you may have.

Thanks for your help, Patrick_Caezza.

Best regards,

Ryan