Goodman GKS9 furnace is giving issues. The LED flashes 3 times which the manual says is caused by blocked flue, blocked air inlet, pressure switch hose, or bad pressure switch. Induction motor works fine. I snaked both outside air lines, blew out the pressure switch hose, and finally replaced the pressure switch. Still same problem.

After further troubleshooting, I discovered that if I turned the furnace power off, waited for the induction motor to wind down, and restarted the furnace with the cover off everything started normally. I could hear the pressure switch operating as the motor spun up. I then put the cover back on and it worked fine.

The only thing I can imagine is that induction motor is weak and needs less intake resistance afforded by the cover being off allowed the pressure switch to close normally.

Any ideas? Thanks!

Snaked out,may not be good enough. A plumbers snake could slide right by a dead bird and you would not even know it. I`ve removed the inducer housing and found birds several times inside the housing. Also, check the hose to the pressure switch for breaks and cracks from dry rot.

Let us know if we can help further.

Well, I couldn't get a confirmed "clean pipe" by normal means... so I cut the pipe in the middle so I could see that it was not clogged at all.

I removed the pressure switch hose and blew it out. It is clean and is only 2 years old.

I guess I will have to remove the inducer housing tomorrow to check for issues. Last chance before I am out of ideas! ;-)

I think Ahmed000,is saying it has a rat inside,, (hazrat ali ke kitne betey they
) if so he want you to save for him,, beats me what he said,