Connecting to a heat pump

[pfenton42]

I have a Lennox AC/Heat pump system and a Honeywell thermostat.  Not sure where to make the connections to the Nest thermostat.  Existing connections are as follows (I don't know how to attach a photo):

Left side:

S = Red
S = White (There are two S terminals on the left)
Y = Yellow
G = Green
C = Blue

Right side:

L/A (A) = Open
O/B = Orange
Aux (W2) = White
E = Open
Aux (W) = Open
K = Open
R = Red

[Patrick_Caezza]

Post a picture of the original thermostat's wiring here

[pfenton42]

[Patrick_Caezza · Accepted solution]

Give this wiring a try.

Red - S - not used

White - S - not used

Yellow - Y to Y1

Green - G to G

Blue - C to C

Orange - O/B to OB

White - AUX to W2/AUX

Red - R to Rc

The S terminals are for an outdoor temperature sensor that the Nest doesn't use.

[Ryan_G]

Hey folks, 

Thanks for reaching out here at the Google Nest Community.

I'd like to jump in here and check how it's going with your Nest thermostat, pfenton42? If you have further questions, let us know by replying to this thread.

Thanks for your help, Patrick_Caezza.

Best regards,

Ryan

[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. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community.

Best, 

Melba

[pfenton42]

Thank you, Patrick!  😁