Im in the 2nd heating season with my luxaire acclimate 9.m model furnace . Now the unit operates for 5-10 minutes & the burner stop on stuck open pressure switch , every thing is OK as far as vents, blower motor,& drain. I have put the fan on @ high speed manualy,upon resetting the fan slowes down when the burner come on?? For 5-10 min. then goes of on safeties ,then the fan speeds up again craizy. Also, even if the tstat is on heating& calling ,the furnace comes on normal calling for coolling 1amber??

At only 2 ears old your unit should be under warranty,, be careful you don`t void the warranty by working on it yourself