One day last week, our carbon monoxide detectors went off, which pretty much scared everybody out of the house.
I went and checked the furnace, and it had shut down, with the rollout switch diagnostic leds signal displayed. When I turned it back on, I notice that the blower was not functioning. The inducer motor was spinning, ignitor worked fine and getting good flames. When I checked the voltage for the 120v heat/fan/ac, none of them showed any voltage. I suspected that a relay on the board (White Rodgers 50A62-121) and gone bad so no power was being distributed to the 120v lines.
So I bought replacement board (White Rodgers 21D83M-843), plugged it in, double checked wiring all around, including thermostat, fired it up. Sweet -- both blower and inducer motors spinning, looks to be good. Nope, within seconds, I got a open rollout circuit error. So I checked the switches, perhaps something could have happened during installation, even though I was nowhere near those wires. Continuity looks good on both switches, just to be sure, I checked continuity back to the 12 wire harness. Looks good. Started up the furnace, nope, still same error. I then bypassed the rollout switches and closed the circuit, same error.
Ok, so I got on the phone with the maker of the board, Emerson, and walked through installation. I did everything correct as per the instructions, so they think I need to replace the board. Terrific.
To double-check, I plugged the old board back in and the open rollout switch problem went away and the furnace fired right up as expected (controlled from my thermostat). My blower still didn't work though so still need a new solution.
I then bought another replacement 21D83M-843 (both Emerson/White Rodgers boards were brand new). Plugged it in today, and guess what, the rollout switch problem is gone! But... the blower isn't working.
Could I be that unlucky to have 3 bad boards - 2 of them brand new? What's the likelihood of that?
Could there be other issues?
Thanks in advance,
Lee
I went and checked the furnace, and it had shut down, with the rollout switch diagnostic leds signal displayed. When I turned it back on, I notice that the blower was not functioning. The inducer motor was spinning, ignitor worked fine and getting good flames. When I checked the voltage for the 120v heat/fan/ac, none of them showed any voltage. I suspected that a relay on the board (White Rodgers 50A62-121) and gone bad so no power was being distributed to the 120v lines.
So I bought replacement board (White Rodgers 21D83M-843), plugged it in, double checked wiring all around, including thermostat, fired it up. Sweet -- both blower and inducer motors spinning, looks to be good. Nope, within seconds, I got a open rollout circuit error. So I checked the switches, perhaps something could have happened during installation, even though I was nowhere near those wires. Continuity looks good on both switches, just to be sure, I checked continuity back to the 12 wire harness. Looks good. Started up the furnace, nope, still same error. I then bypassed the rollout switches and closed the circuit, same error.
Ok, so I got on the phone with the maker of the board, Emerson, and walked through installation. I did everything correct as per the instructions, so they think I need to replace the board. Terrific.
To double-check, I plugged the old board back in and the open rollout switch problem went away and the furnace fired right up as expected (controlled from my thermostat). My blower still didn't work though so still need a new solution.
I then bought another replacement 21D83M-843 (both Emerson/White Rodgers boards were brand new). Plugged it in today, and guess what, the rollout switch problem is gone! But... the blower isn't working.
Could I be that unlucky to have 3 bad boards - 2 of them brand new? What's the likelihood of that?
Could there be other issues?
Thanks in advance,
Lee
source https://hvac-talk.com/vbb/showthread.php?2224046-I-m-losing-my-mind-Furnace-control-board-challenges&goto=newpost
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