Thermostat replace

[DonJon99]

Hello everyone! Need a little help please.
Iam trying to replace my Coleman thermostat to my roof Ac with a digital one. The Ac unit has 4 connections Y-compressor GL-low fan GH-high fan B-unknown. The wires coming out of wall where thermostat was is 4 small wires that go to Ac and two bigger wires 12v+ and 12v-
The thermostat is plain nonprogrammable digital with these hookups. B O G Y W R RC. What goes where? I was thinking:
AC UNIT.--------------THERMOSTAT
Y ----------------------Y
GH--------------------G
GL---------------------- Not using low speed right now
B.------------------------ I don't know???

POWER.-----------/---- THERMOSTAT
12+.--------------------R&RC jumper installed
12- ------------------ I don't know????

So basically I think I have it right but the 12- and the B wire. Thanks for any help!

[DonJon99]

Got it!!! I hooked the B on Ac unit and the 12- volt ground out of wall together to the B on thermostat to make it work. Thanks biscuit for the help.

[DonJon99]

Have a separate furnace with its own thermostat. Wasn't sure if I could run it off the same thermostat as the Ac unit. No the Ac unit doesn't have a heater.
The new digital thermostat is a Honeywell RTH111

[Old-Biscuit]

Your thermostat doesn't control furnace also....WHITE wire???

Here is a Coleman to Hunter......you don't state which digital t-sat you are using???

[1492]

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