I have a new Goodman 80% natuaral gas furnace, GMH80451ANA.

After installed, it fired right up and ran for about 30 minutes and burned off the smell from the exchanger tubes. Ran it a second time for another half hour or so, then it would not fire up again. The only thing I did was to change the blower leads on the LO heat and the HI heat to slow the blower down.

Now, the LED is throwing a 3 blink code which indicates a pressure switch stuck open along with the draft inducer fan running constantly. The odd thing is that the inducer fan does not run.

I think it's the control board.

I applied power directly to the inducer fan and it runs fine. I checked the pressue switch and it opens and closes properly, the fuse in the control board looks OK, and by process of elimination, it leaves the board... do you agree?

Thanks in advance.

Now, the LED is throwing a 3 blink code which indicates a pressure switch stuck open along with the draft inducer fan running constantly. The odd thing is that the inducer fan does not run. This statement is contradictory so I am not sure what to think. Does the diagnostic light start to blink almost as soon as power is turned on? Could the pressure switch be starting in the closed position instead of the open position?

I double checked and the pressure switch starts open, and stays open since the inducer fan never starts up like it's supposed to. Also, if the pressure switch was stuck closed, the LED would give a 2-blink code (and the inducer would not run). I'm thinking it't the control board since the inducer fan doesn't start when it should even though the pressure switch is open. When I apply power directly to the inducer, it does run.

The LED is on when power is given to the furnace. Then the thermo calls for heat, and the LED goes off, I hear a little click that sounds like a small solenoid or something, then a second or two later, the 3 blink code on the LED, and nothing else. The inducer never even starts to run.

I'd hate to spend all the money on a control board, and then have the problem persist.

Thanks.

Try Fan On. If the fan doesn't come on, it is possible the 120 isn't making it to the control board. You may have knocked its plug loose changing the blower plug. The inducer relay must have 120 on the line terminal to switch power to the inducer.

Thanks, labman.

Yes, the blower comes on when the thermo is set to "fan ON".