no green wire coming out of wall has blue wire

[JimRon]

I have a rh ,w, y,blue coming out of wall for thermostat . What does the blue wire go to . I put in the green connection and no help. 

[zoeuvre]

Hi JimRon, 

Thanks for posting here in the Community forum and for showing interest in our Nest Thermostats. Are you located in North America or Europe? What is the make and model of your HVAC system? Also, to identify what the blue wire is for, check on your HVAC control board where it goes.

Keep us posted. 

Best,

Zoe