Hi, I've been searching for a few days & am unable to find what I'm looking for.
I have a 7 year old furnace. lennox ultra 5 advantage.
Went to turn on heat & nothing!!
The led trouble code is 3 blinks = "Pressure switch stuck open 30 seconds or longer after call for heat. on/off switch in "off" position during call for heat will generate this code ( this is right out of the furnace manual)
After researching I believe it is one of two items:
1. Draft inducer fan is bad.
2. Pressure switch is bad.
I cannot tell if the Draft inducer fan is actually spinning. I can hear the fan unit "hum" & it is very hot to the touch. However I am unsure if the fan is actually spinning!
I tested for continuity (w/ohms) from the black - green & white-green wires & found no continuity on both. There was continuity from black to white.
I am wondering how else I can test the fan to see if its working?
2. The tubes don't appear to be cloggeed, I blew in the one coming off the inducer fan & i can audibly hear the pressure switch clicking. Not sure how to test the switch with an meter.
Any thoughts / tips would be great. I'd like to try & figure this out without having to call in the repair man