I have a Maytag High Efficiency Furnace model PGFITE120CVC (condensing) It is one year old and is 95% efficency. Worked fine last year but after starting up this Fall it is producing a fine white material that is blowing out of the vents. You can only notice as it is layering out on tables etc. My A/C installer came to see it and looked at the plenum after the A/C coil and you can see a fine white powder(looks like dandruff ). Vacuumed it out and it is still coming out. Does not do this on A/C are fan only so it seems that it has to be related to the furnace. The intake plenum is clean Any ideas my A/C installer who is very is baffled so far. he is coming back next week. I asked for a CO check but I think he did not do it. I am worried that the burner could have a break .