Furnace does not always start correctly. Sometimes runs fine. Other times won't start. Tried to clear inlet pipe with shop vac, no clogs I could find.
Did find a dead bird in furnace at end of inlet. Removed and cleared inlet pipe.
Could it be that the pressure switch is clogged or intermittent?
Once it does start, it will remain running until the thermostat shuts it off.
How do I debug the pressure switch?
Mostly code 12 when fail, one time code 31.
Thanks