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The first thing to try is to turn the power off then connect the leads on the R & W terminals on the thermostat. If you don't have terminals designations and only have 2 wires connect them together then turn the power back on. If that doesn't work then turn the power off again and try connecting those 2 terminals on the furnace with a short piece of wire. Then put turn the power back on. If you still have no response the you'll need a multi-meter to troubleshoot this any further.
Sorry for the misplaced text at the begging of my response. I've corrected it. We can proceed when you're ready
That doesn't indicate anything other than it's the contacts are closing. It doesn't mean it's actually closing the thermostat circuit. If you want to get to the bottom of this then the place to start is with my instructions.
Did you try both options? at the furnace as well? If you did then you need a multi-meter to troubleshoot this further. Do you have one?
Then there's not much more you can do. One other thing you can look for is rollout switches above and just outside the burner chamber (see attached picture for a typical one). You can try pushing the small button in the middle of the 2 wires. If it clicks you have reset it and the burner will fire up with any luck.
This is a really old furnace if it has a thermopile (what you're describing). The most likely cause of the problem you're describing is a weak thermopile. The thermopile generates all the power (less than 1 volt) to operate the gas control valve. It does this when it heats up. When they get weak they don't produce enough voltage to make the round trip to the thermostat and back. We would replace thethermopile first in a case like this
You're welcome. Your unit is far too old for there to be any available specs on it. You described a thermopile not a thermocouple.
You still need to replace it. Wire brushing it off is a stop gap measure at best. It will fail probably at the least convenient time, like when everything is closed and you can't get parts. It's not a good idea to go into the Winter with an old thermopile that's already been acting up.