I'm not sure of the exact model of my Goodman furnace, but here is the problem. The new furnace was installed this summer (2010) and it is mounted in the space under the house in Big Bear Lake, CA. Elevation approximately 7300' night time low temps approximately 25 degrees but certainly can get colder. Small house approximately 1100 square feet. The furnace will cycle on and off and work fine most of the time, but 15-20% of the time the furnace fails to light and the fan just comes on and circulates unheated air. At this point I will turn the thermostat / unit to off (fan switch is always in auto) and shut it down. After waiting 5 minutes or so I will turn the thermostat back to heat and see if the funace will kick back on. I have to repeat this cycle sometimes 7 or 10 times waiting anywhere from 5 to 30 minutes between cycles before the furnace will eventually light and operate correctly. I have already changed the thermostat, and it is not a programable thermostat, so it simply has an off, heat, or cool to operate the furnace (and I don't have A/C), and an auto or on to operate the fan. Please help, for it gets mighty chilly in the middle of the night monkeying around with this thing when it's 10 degrees outside. Thanks.