MTHook, look back near the beginning of this thread and look at the diagram I posted of my thermostat conversion to a Hunter Digital. All basic thermostats have similar designations and normally +12 VDC is connected to the R terminal and for basic RV furnace and air conditioner the R and RC connectors are connected together with a jumper. If your thermostat runs on its own AA batteries you should not require a ground connection; but if it uses the coach battery for power you will require a ground wire too (B terminal usually). I am not sure why your diagram says battery to G terminal as that usually is to provide power from the thermostat to either high or low speed fan on the air conditioner via the switch you show. To air conditioning compressor for call to cool (Y); to Furnace for call to heat (W). Hope that helps you out.
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