# Thermostat: Honeywell T841a -> Gen 3 Nest



## grandlarsony (Jun 8, 2016)

Hi,

General wiring question.

Original Wiring to the Honeywell (model T841a):

Orange Wire -> O
Brown Wire -> B
Blue Wire -> X
Black -> E

The rest are connected correctly, but i'm not a 100% on the correct terminal connections to the nest for the ones referenced above.

I have: 
O (orange) going to Ob, 
E (black) going to *, 
X (blue) going to C, 
Brown currently not connected. 

Please advise correct connections

My Air Conditioning is running, but I feel like it's not as responsive as it should be (not shutting off once it's hit the designated temperature).

I have read a lot, but I cannot find a definitive answer. I've read that B is supposed to be the common wire, but that sometimes O can actually be the common wire and it's throwing me off. Also, in regards to B i've read that the common wire provide "direct power to the thermostat". What's the difference between direct power to the thermostat and the R wire that provides power in general. 

Greatly appreciate the assistance.


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