Richard, what do you think about the mismatch between the JM, JJ an JB codes and those in Winnebago's list of wire codes and colors?
I don't have a problem with the thermostat, Winnebago and furnace colors not being the same as long as the colors match up correctly in the two connectors and on the thermostat terminal block.
Given a long enough test wire w/alligator clips and a multimeter, one could test continuity between the two connectors.
I see no problem with the mismatch that would keep things from working!
BUT it certainly makes life more difficult than we might like?
Instead of just trying to remember that pins 1,2,3, are JM, JJ, and JB like they are on the furnace end, we need to keep in mind that those three wires are found on pins 2, 3, 1, at the thermostat end!
If life were simple, the folks who do the pins for the furnace and the thermostat would agree which way they wanted to build things!
Kind of like dealing with Celsius and Fahrenheit except far less reason and history? Out here in the real world where us rookies try to figure things, it just adds another layer of potential screwups!
If we look for power on the plug at the furnace, it should be on wire JB at pin
3. But if we want to look for that same power at the thermostat plug, we should find it on wire JB but on pin 1 of the plug for the thermostat!
That makes life hard but then it also throws in some more doubt. If this thermostat builder and furnace builder did not agree with how to wire the plugs, what do we get if we buy a different brand thermostat and that builder wires their thermostat in yet another way?
It's almost like we are trying to put a hubcap from a Chevy on a Ford! The only way we can find out is to try it to see if it works?
That's not a real happy thought!
Then we get into the labeling on the board. When it is labeled 12 positive, that seems clear as our RV operate on positive voltage.
But that 12V negative seems like they are speaking a different way.
If you test from 12 positive to 12negative you get 24 volts difference.
That makes me believe the 12 negative is actually just what most call ground or zero! It is the negative side of the 12volt system but not negative in the way we normally speak. We mostly use ground as the reference and measure from there in the RV /automotive world.
Do you have a brand and model number for the furnace and thermostat you now have?
I would expect there to be a wire to bring 12VDC from the fuse to the furnace and I think I've always found that with just taking the outside cover off.
But if we can get a manual for the specific furnace you have, it often shows a troubleshooting chart as well as where and how to wire when we install the furnace!
