Nest learning thermostat not heating/wiring errors

[Grasoon]

I’m having heating/wiring issues. The display works, as well as the fan, but once I try to turn on heating functions is when I tend to get an Error for the OB or R wiring. All wires are in their respective places, but I have no C wire. 

I’ll post a picture of the preexisting setup.

 

[Patrick_Caezza · Accepted solution]

I'm going to guess that you have a conventional system and not a Heat Pump system

Try this wiring

Green  - G to G

White - W to W1

Blue - B to C

Yellow - Y to Y1

Red - R to Rc (jumper to RC not needed)

[Grasoon]

Thank you for your assistance. I actually swapped the blue to the C position last night  and it’s been working flawlessly 👌🏾

[MelbaDT]

 Hey folks, 

Thanks for your answers, Patrick_Caezza and dhx227.

Grasoon, glad to hear that you've sorted it our and thanks for keeping us in the loop. Feel free to reach out again if you need more help. 

Best, 

Melba

[MelbaDT]

Hi, 

I haven't heard from you in a while so I'll be locking this thread if there is no update within the day. Should you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community.
 

Best, 

Melba

[dhx227]

What is that thermostat?   The problem with 'B' is that is could mean Black, Blue, or Brown... 

However, it's very rare to have (O)range AND (B)rown...   So, that leaves it more likely to be (B)lack or (B)lue both of which are commonly the color for (C)ommon.

If you happen to have a voltmeter handy, it's very easy to tell if the Blue wire is the common as connecting a voltmeter (in AC mode) to the Blue wire and the Red wire will show 24vac.

Alternatively, you can go to the furnace/heat pump and look at how the thermostat wires are connected there.

[Patrick_Caezza]

That's a standard Trane type of thermostat and they use B as the common wire. Never just go by the wire color as there is no standard.

[dhx227]

Also why B is a horrible letter...