O and B wiring help please! 😬

[CO_AZ]

Trying to help set up my grandma's Nest in AZ and running into trouble. Old thermostat has O,B,W,G,RH wires. I tried connecting B to the C and the O to the O/B as others had success with. I received an error from Nest looking for the Y and moved the W to the Y. When we turned it on, instead of AC it was blowing heat. Help!!

[CO_AZ]

Nest tech help had me rewire back the W to original place. But then received the error code E77 looking for a Y1 wire. I contacted support again and they stated I need to have a dedicated Y wire added. It's there an easy fix to this without calling a specialist?

[Subiewrx22]

Do you have a picture? Also do you have a yellow wire. 

[CO_AZ]

I do have a yellow wire and a picture: https://photos.app.goo.gl/VoFm8sjPH8QFnEhL9

It is a heat pump system. I've also tried moving the yellow wire to Y but when turning on the AC all we had was the fan and no cooling. 

[Subiewrx22]

Here is my wiring.https://photos.app.goo.gl/JiainJqUwfccshto7 

[zoeuvre]

Hi folks, 

Thanks for chiming in, @CO_AZ. 

@Subiewrx22, oh no! Let's see what's going on.

Are you located in North America or Europe? What type of Nest Thermostat do you have? Since you have a heat pump heating system, your thermostat wires should be wired as follows: 

• Yellow wire to W or W1
• Green wire to G
• White wire to OB or *OB
• Blue wire to C
• Red wire to R or RH

Let us know how it goes.

Best,

Zoe