my furnace is not coming on, it starts (the blower) the temp is on hold like it was programmed and I cannot manually set it higher and have it come on. I've tried following the directions on the cover 97-4730 Rev A and set it back 30 minutes to come on then upped the temp and still nothing. I've held the Ahead and back together which did cancel the program time/day program, then manually upped the heat - still nothing. Furnace just serviced less than month ago.