Flaky Furnace Thermostat
I have a Suburban gas furnace in my 4-year old 5th-wheel. The thermostat name on the front panel is "RVComfort.HP". When heating on propane only (that is, not using the heat pump), four times in the p...
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The two wires that go on the furnace-only Tstat are not pos and neg. It is one pos 12v wire that is cut with the Tstat inserted so that it switches that one wire.
The two blue wires heading from the power end of the furnace to the Tstat is like that. I am guessing your two blues go to some complicated connection place that has different colour wires coming out of it to that complicated OEM Tstat that runs all those things, so you can't tell which is each end of the "one" wire to use with the new furnace-only Tstat.
IMO put the OEM wires back where they were, and start over by grabbing the two blues closer to the furnace where you can tell which they are, cut them there, add more wire to each blue where you cut them going to the new Tstat location. That should get you furnace only.
Now the trick would be whether the OEM Tstat will still run the air and the heat pump properly, except now it won't go to furnace when its "gap" gets that way. It seems your OEM's brain isn't working right for how it switches between heat pump and furnace. That leaves you to pick the heat source, if the OEM Tstat still runs the heat pump ok.
I don't know where that brain is located. You replaced the OEM Tstat and nothing changed, so the broken brain must be elsewhere. Not a clue, but could be a control board in the mix that is not in the Tstat. Or as was suggested, there is bad wire connection to the OEM's brain that did not get fixed by replacing the OEM Tstat.
Some of those boards have wire connections that slide on to the edge of the board where there are contacts. Sometimes pulling them off the edge and cleaning the contacts and putting them back on is all it takes to get things going again.
The two blue wires heading from the power end of the furnace to the Tstat is like that. I am guessing your two blues go to some complicated connection place that has different colour wires coming out of it to that complicated OEM Tstat that runs all those things, so you can't tell which is each end of the "one" wire to use with the new furnace-only Tstat.
IMO put the OEM wires back where they were, and start over by grabbing the two blues closer to the furnace where you can tell which they are, cut them there, add more wire to each blue where you cut them going to the new Tstat location. That should get you furnace only.
Now the trick would be whether the OEM Tstat will still run the air and the heat pump properly, except now it won't go to furnace when its "gap" gets that way. It seems your OEM's brain isn't working right for how it switches between heat pump and furnace. That leaves you to pick the heat source, if the OEM Tstat still runs the heat pump ok.
I don't know where that brain is located. You replaced the OEM Tstat and nothing changed, so the broken brain must be elsewhere. Not a clue, but could be a control board in the mix that is not in the Tstat. Or as was suggested, there is bad wire connection to the OEM's brain that did not get fixed by replacing the OEM Tstat.
Some of those boards have wire connections that slide on to the edge of the board where there are contacts. Sometimes pulling them off the edge and cleaning the contacts and putting them back on is all it takes to get things going again.
