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Confirm need to replace Nordyne 624591-B furnace control board before I buy?

Confirm need to replace Nordyne 624591-B furnace control board before I buy?


  #1  
Old 09-17-11, 10:00 PM
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Confirm need to replace Nordyne 624591-B furnace control board before I buy?

I discovered that our cottage furnace won't fire up -- this is first attempt since last season, but we haven't had any problems over the last 6 heating seasons.

Furnace is a Tappan model GR6K072C-12, manufactured in June 1998, and hasn't been serviced in the 6 years we have owned this place.

I tried checking several different things, and I THINK a faulty circuit board is causing my troubles, but it would be great if I can confirm before buying the part.


What I've tried so far ...
- confirmed that call for heat from thermostat correctly triggers 24VAC to W terminal block on board

- verified continuity on the 24 VAC limit control circuit (over-temperature limit switch, flame roll out switches and blocked vent switch are all closed)

- confirmed that pressure switch will operate correctly; open without pressure and closed with any vaccuum; tubing is also open and unclogged

- applied 120VAC directly to inducer motor to confirm motor will run when energized

- found NO voltage at molex plug to inducer motor, so board never energizes inducer


Because inducer motor is very first step in sequence for this furnace to start, I can't get past square one. Pressure switch will not close without inducer running, so igniter is never energized.

Status light on circuit board flashes twice, but this code simply means that pressure switch is "stuck" open, and disregards the fact that inducer wasn't started to cause the pressure switch to close!


Any advice or suggestions are appreciated.

Thanks
 
  #2  
Old 09-17-11, 10:20 PM
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A couple things I didn't include in original post

I hadn't seen this forum's "read this B-4 posting" entry, so I didn't think to include the following couple of items (sorry):


- Furnace is a natural gas, forced air downflow unit. (no central air conditioning)

- Thermostat is a simple mercury "analog" manual dial that WAS replaced new with the same style when we bought the cottage 6 years ago.


P.S. - It's getting downright chilly now, so I'm putting on my long johns and heading to bed! Thanks again for your suggestions or anything else I should check before buying a new circuit board.
 
  #3  
Old 09-18-11, 05:41 AM
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if you have no 120V output to the inducer then I would say, yes, you need a new control board.
 
  #4  
Old 09-18-11, 03:00 PM
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I presume you have che4cked to verify that you have 120 VAC being applied to the proper input to the circuit board.

If so, I's say you need a new circuit board.
 
  #5  
Old 09-19-11, 07:05 PM
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Thanks for your concurrence that my furnace problem does appear to be the control board. Thanks also to SeattlePioneer's comment as another confirmation.

I bought a replacement control board today for installation this weekend when we're back at the cottage, and will report the results then (hopefully positive).

Thanks again!
 
  #6  
Old 09-23-11, 08:41 PM
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Red face Nice and toasty again ...

After I installed the new control board, I'm glad to report that everything is working as expected, so we again have heat whenever we want it this season.

Thanks much!!
 
 

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