# Honeywell RTH9580WF to Goodman (Janitrol) GMP075-3 Furnace and AC installation help



## sersel (Aug 30, 2015)

I just purchased Honeywell RTH9580WF and tried to follow Honeywell's instruction on how substitute G-Wire for C-Wire






My current thermostat (Honeywell Magicstat CT2400) has 4 wires - Y, R, G, and W.

Furnace details:
Goodman GMP 075-3
Control board: B18099-13
Transformer : B11416-00

I know in order to use the new thermostat I need a C terminal where I need to move the G wire to, but I can not find a connection for it on my furnace. I searched around various places, but could not find any clear explanation. I also tried the Honeywell tech support, they recommended me to go to Goodman to find out where the C terminal is. 

I also need to know how to put a jumper between Y and G as I do not see a Y terminal on the control board. I will be running both AC and heater with the new thermostat.

Any help will be highly appreciated. Many thanks in advance


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## charlie1776 (Jan 19, 2011)

G is for you fan. C is common. That will be the ground side of your transformer. Subbing G for C will short your transformer out and you'll let the magic smoke out. That blue wire coming off your transformer goes to C. The green wire coming from the control board will go to G. Red will go to RC and should be jumped to RH as well. That is your 24V control power. White will go to W1 which is your first stage heat. Yellow goes to Y and will go to your condensing unit along with C.


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