RV Repair: suburban furnace, coleman t-stat, suburban furnace, continuity tester

Question
My newly purchased used r.v. furnace will not run. I thought it was because it was out of propane, but the tank is full now.I put a continuity tester across all possible teminals of the t-stat connection and none show a circuit with the stat in a demand setting, i.e. heat, auto, max temp. Fan motor runs w/direct connection to 12 volts, relay passes current to motor(the black wire to motor surely is not energized or the fsn would run. Any ideas? Thanks

Answer
Robert, I am assuming that you have a Coleman air conditioner on this unit. If so Coleman doesn't get power from the air but has a 12 volt source for it. If you can't find any continuity anywhere at the CT-Stat when you have it in heat mode then I would say you have a bad T-Stat. Usually in units that use Coleman they have the wires separated in 2 harnesses because they run in different directions. You might be able to find the wires for the furnace when you pull it off the wall. If you can't find the right one you can test for continuity between there and the furnace wires. What you will want to do is connect the 2 wires for the furnace. That should force it on. If it does the T-Stat is bad if not make sure there is power to the furnace on the red wire and out on 1 of the blue wires at the furnace. You can always jump the 2 blue wires at the furnace as well, but that wont tell you if the wires between are still good. There will be a 3 wire connector that hooks up on the side of the furnace, right side as you are looking at it. It unplugs by pinching the ends together and releasing the catches. If you don't have power there try and make sure the fuse for the furnace is good. Hopefully you will be able to find the trouble with what I have told you but if you still have trouble feel free to ask and I will guide you through the rest of the diagnostic procedures. Thanks, Bill