Goodman furnace constant blinking led.
I have a Goodman Model # GSM100-4 furnace that has been a pain the tail. This week I went to start it up and I am getting a constant flash on the control board. I have an old, what I thought, was a good board that I swapped out. Still the same problem, constant flashing. I tried swapping the control transformer leads around- no luck. This unit worked fine this spring when we switched to cool.
The unit will go through it's normal start-up procedure with the blowers running, ingniter coming on, gas valve opens flame, ingniter goes off and within a few seconds the gas valve closes.
So far I replaced the flame sensor. This was before I noticed the flashing led. This was the problem on start-up last year and the reason I have another what I think is good circuit board.
All wiring appears to be good and tight, all connections sprayed down with contact cleaner.
Any help would be appreciated.
Thanks in advance,
John