[4Joseph]

Hi,
I have a 5 year old Concord 80 Plus Gas furnace that is not functioning correctly. During the day, furnace works fine. However, as the temperature drops at night, the furnace operation becomes erratic!

As I raise the "t-stat", the inducer motor starts & after 12 sec. I hear the "click" of the pilot flame ignitor. After 3 sec. the ignitor tries to initiate the step for furnace to fire. I see the blue flame of the gas for 1 sec. but the gas does not stay completely lit for the entire temp cycle set on the upstairs "t-stat".

When I manually disrupt the continuous cycle by turning "off" & then "on" the wall switch by the furnace after a minute, the furnace works for a couple of hours! Also, I open the top cover of the unit & that seems to work for a couple of hours as well.

What's the issue? Bad wiring? Faulty flame sensor?
Help!
Joseph