Gas and Oil Home Heating Furnaces - Goodman Dependable 92

I have a Goodman GMPN 088-4 REV B furnace and am getting a vent blockage blink. I have taken every hose off and checked. I have checked the trap, replaced the pressure switch and even checked the 2" PVC vent to the roof all to no avail. Am I missing something? Could the Circuit board be Bad?

Take the hose to the pressure switch off the barbed fitting on the inducer motor housing. Use quite a small drill bit to poke in that fitting, taking care to get it down inside the housing near the blower wheel. move the drill bit around to clear away any accumulated corrosion.

Put the tubing back on and give it a try.

I've done that too. no blockage

Take off the inducer motor and look for any debris in the end of the heat exchangers. Double check that the pressure switch fitting is clear by running the drill bit down until you can see it inside the housing. It can get hung up part way down if you aren't careful.

Remove the burners and inspect the heat exchangers with a mirror to look for any soot or debris accumulations.

Inspect the fan wheel of the inducer motor for any accumulated corrosion, detrioration or debris. Spin the inducer motor fan for any indications that it's stiff from wear or failed bearings. Apply power to the motor and verify that it appears to start easily and comes up to full speed easily.

With a stiff wire brush on a flexible handle, remove any loose scale from the heat exchanger at both the flue and burner openings.

Use a 1/2" diameter brush to remove any deposits from the secondary heat exchanger. This brush needs to be long enough and flexible enough to push all the way through the secondary heat exchanger.

Check the primary and secondary heat exchanger for any visible cracks or holes.