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My furnace is not working properly (ICM2805A control board, or Nordyne 624631A). When I turn it on, the inducer motor will start spinning and shut down immediately, the board will reset, and try again in about 30 seconds. The igniter never gets to glow. This loop repeats forever. Every time the inducer stops, the status light goes off for a split second and back to solid red.

Things I tried, in order:

  1. I check all the safety switches and they are all operate correctly (closed by default). Also the whole safety circuit is closed.
  2. The pressure switch works well. With a multimeter, when I gently suck the pipe, it clicks, and the circuit opens.
  3. I replaced the pressure switch with a manual switch. I open it manually once the inducer starts, but I still have the same problem.
  4. The resistance of the glower is of 70ohm, but it never turns on.
  5. The problem persists when I disconnect all thermostat wires, I manually connect R to W directly on the board.
  6. I bought a new ICM2805A board, and the problem is till there with the brand new board.

At this point, I do not know what else to check. Any ideas?

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  • 1
    Guessing problem with number 4. Does it get power? A furnace technician can probably find the problem in a few minutes of testing.
    – crip659
    Commented Nov 18, 2021 at 21:54
  • I disconnected the ignitor, and plugged it directly to ~120V, and it does glow. So it is not a faulty ignitor. The interesting part is that without the ignitor, the board does not reset and does not shut down the inducer motor. I didn't let it run for too long without ignitor, in case it wanted to turn the gas on. However, at no moment it sends power to the ignitor, the multimeter shows ~1V.
    – formiga
    Commented Nov 18, 2021 at 22:45
  • Looks like a problem with that circuit on the furnace, maybe a switch is wonky and only works partly or a wire not complete. Had a switch like that on a new heater, would only complete circuit sometimes. Even testing with meter would be working/not working.
    – crip659
    Commented Nov 18, 2021 at 22:52
  • Problem solved. It was the ignitor connector. It was probably not making a good contact. After I put back the ignitor, it all worked again. I will replace the connector for some temperature rated wire nuts.
    – formiga
    Commented Nov 18, 2021 at 23:13
  • 1
    Write this up as an answer. Might help other people.
    – crip659
    Commented Nov 18, 2021 at 23:23

1 Answer 1

Reset to default
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Problem solved. It was the ignitor connector. It was probably not making a good contact. After I put back the ignitor, it all worked again. I will replace the connector for some temperature rated wire nuts.enter image description here

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  • I would suggest that if this is the connector installed by the factory, then it is already designed to withstand whatever level of heat it should be exposed to under normal circumstances. Therefore, there shouldn't be any need to replace it (by clipping it off) with any other type of temperature rated connectors.
    – FreeMan
    Commented Nov 19, 2021 at 0:39
  • Had an ATV that stopped working. Found out after much testing/looking a connector like that open up about a 1/16 inch, still looked connected and still locked together. Pushed it together and ATV took off.
    – crip659
    Commented Nov 19, 2021 at 0:57

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