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Discussion Starter · #1 ·
Armstrong G1N80BU100D14B-3A s/n 1607F04191

The unit started working intermittently over the last week and finally refused to fire yesterday. The LED inidicator on the control board blinks 7 times indicating lockout due to no ignition. The limit switches are all closed. The induced draft motor starts, the gas starts to flow and then it shuts down. I replaced the hot surface ignitor thinking that was the problem, but there is no change. I can stick my propane torch in and light it manually and it will stay lit for a while, but still won't run normally. I have cleaned the flame sensor rod as part of annual maintenance. Any ideas before I throw a control board at it?
 

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Discussion Starter · #5 ·
thank you all for your replies. I have cleaned the flame sensor. There is no flame to sense before it shuts off. The sequence as it goes right now is: induced draft motor turns on, the pressure switch closes allowing gas to flow, and the unit shuts off. All happens within 2.5-3 seconds. The valve is a Honeywell VR8205S2338 with only two wires. I don't think that is a smartvalve.
 

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HSI is probably bad. It should be glowing before the gas valve opens.
 

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Discussion Starter · #7 ·
I thought it should. I replaced it before I bothered to put a multimeter on the wires that connect to it. I have a nice new white rodgers 21D64-2 HSI installed in the place of the old one. It still doesn't work because there is no power to light it.
 

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Discussion Starter · #9 ·
No voltage to it. It seems that the startup order is out of order with the induced draft motor on for only a second before the pressure switch allows gas flow. I'm not sure I remember correctly, but I thought the draft motor ran for 10 seconds or so before the unit fired.
 

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Probably have a bad circuit board or poor connections on it or a poor ground to the board or furnace. Sequence of operation is that the inducer fan relay starts the inducer which is programmed to run for at least 30-60 seconds to purge any gas from the chamber. Press switch closes but the board delays igniton until the purge cycle is over. Then the HSI warms up and gas valve opens.
 

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Discussion Starter · #11 ·
Control board replacement

I was forced to pay for a service call to tell me that the control board was bad. It is covered by warranty, and the unit runs great again. I hate paying people to tell me what I already know. Thanks to all of you who replied.
 
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