# Thermostat conecting 3 wires



## jacobo 348 (Aug 15, 2009)

I want to change my mercury thermostat to a digital White Rodger 1F86-344.
I have only 3 wires R,Y,G,. the digital thermostat diagram for 3 wire cool only system tell me:
to jumper RH and RC terminals shold connect to my R wire,
Y terminal connect to my Y cable
and G terminal connect to my G wire.
Then it tells me to connect de C terminal?? I do not have this cable and I do not thing I should jump G and Y to C., i am afraid to short the AC sysstem what should I do? here is the link to the diagrams
http://www.white-rodgers.com/wrdhom/pdfs/06_Cat_pages/Cat_06_pg0178.pdf

Thanks


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## Basementgeek (Feb 7, 2005)

Hi and welcome to TSF :wave:

Don't jumper G & Y to C. 

It could help if you could find a wiring diagram for the old thermostat and post it.

BG


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## jacobo 348 (Aug 15, 2009)

I do not have the wiring diagram for the old thermostat. It is an mercury mechanic thermostat and it was conected R,Y,G,. 
Thanks again


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## speedster123 (Oct 18, 2006)

Old thread but-
Call White Rodgers
The C terminal is the neutral/ground coming from the 24 volt transformer.
Do not jump any other wire to it.
You might leave that alone, but call.


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