O/B wire on a Nest

[Rgrochan]

I replaced my old non programmable thermostat with a Nest thermostat. The old thermostat used C, O, W, Rh jumped to Rc, G & Y. Connect the wire to the Nest, minus the jumper. With the O wire connected, the Nest is saying the I have Heat pump but I don’t. Going through the test, the Nest keeps trying to run the AC. I’m thinking that the Nest thinks it’s the heat pump. Get a error message of T04. If I remove the O wire the Nest sees that it heat and AC and test okay and runs great. 
Trying to figure out why the O connection I on the old thermostat and do I need it connected. 
The system is an Amana. Furnace I model AMVM970804CN. AC is model ASX16031. 
Any help would be appreciated. 

[Markjosephp]

Hello Rgrochan,

Thanks for reaching out. I understand that the wiring setup can be confusing, but I'd love to help.

O and B wires control when your heat pump cools or heats your home, and I can confirm that you only have a furnace type of system based on the make and model you've given. In this case, you can leave the brown wire disconnected as you don't have a heat pump system. Make sure to tuck it in behind the wall and not touch the other wire.

If there’s anything else I can help you with, please let me know.

Regards,

Mark

[Markjosephp]

Hey there,

I wanted to follow up and see if you are still in need of any help. Please let me know if you are still having any trouble from here, as I would be happy to take a closer look and assist you further.

Thanks,

Mark

[Markjosephp]

Hi Rgrochan,

I'm checking in to make sure that you've seen my response. Please let us know if you have any additional questions or concerns before I lock this thread in 24 hours. 

Thanks,

Mark