RogerThat
Nov 27, 2010, 11:44 AM
York (Model: P4HUA1ZN06401B) vertical natural gas furnace. Observed that the burner on right, by the glowing starter, starts properly but the other three burners do not light and since the thermocouple on the left does not start, the gas is stopped in about 5 tyo 10 seconds. I cleaned all four nozzels and it did not help. I find that if I blew slightly into the combustion chamber when it was attempting to start and the other three burners started and continued to burn until the thermostat was satisfied. Note: The combustion blower fan is operational.
KevinMI
Dec 28, 2011, 03:13 PM
If the second nozzle will not light, then neither will the third or fourth nozzle.
You said you already cleaned the four nozzles, but you could have some hidden debris (rust flake) inside the pipe or inside the second nozzle. Or there may be a bit of moisture inside the pipe or second nozzle, and cold air could freeze just enough to plug the second nozzle. If it is slightly frozen moisture, you will not be able to see it or feel it.
In either instance, you might consider taking the nozzles off and running a quick blast of clean & dry compressed air through the pipe, and then replacing the nozzles.