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You should get an error code on control board in blower compartment indicating what has failed.Can you check and let me know pattern of flashing?
Control board is mounted on blower housing.You may have a window to peep in to see light.
OK this is telling us the pressure switch is not closing or staying closed.
This could be
caused by a number of problems: faulty inducer, blocked vent pipe, broken
pressure switch hose or faulty pressure switch.
1.If pressure switch is open, burners should not be on.
2.First lets make sure the small vent motor is coming on.
3.If so lets try this.
Next I want you to locate the pressure switch. It will be a small round canister with a hose attaching it to the inducer housing. Remove hose from inducer housing and leave it attached to the pressure switch. Power off and back on to reset board again, Then call for heat at thermostat. Allow inducer to start then suck on the end of hose still attached to pressure switch and see if switch will close and burners ignite.
OK does igniter glow after you hear the click?
Look closely at igniter and see if there is a broken or burned spot.
When sucking on hose still attached to switch do you still get error code?
D you have a meter to verify the switch contacts are closing?Either switch is bad or board is not reading it closed.
Check to see if the circuit has continuity between pins 10 and 7 on each side of the pressure switch. See below
Sentence did not complete. Please explain
OK looks like pressure switch is the problem You will need to replace it.