On my 2013 coach I think the original Coleman analog thermostat had very short wiring into the wall cavity OR was stub wired into the wall and then the final connections to the main device cables (to furnace, air conditioner etc) were made with wire nuts. So when I did the conversion I used same color wires to extend slightly and rewire to the new thermo contacts (wire nuts again but taped and strain relieved). Sounds like you were careful on the one for one conversion, but you also said you disconnected the batteries I thought before you did the wiring conversion? If you don't see +12Vdc on the R, RC, RH thermostat terminal (to ground B) with a voltmeter then you have just blown a fuse as Tfryman advised.....or have a bad connection; use/store is off etc. Just a matter of tracking it down.
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