Lennox Pulse21 furnace (intermittent heat)

[countryboy10]

My Lennox Pulse21 gas furnace heats fine through the day following the thermostat setting although it usually hesitates a couple times before actually firing up. The main problem is in the morning when the thermostat is set-up about 4* higher than the night time setting, sometimes the furnace won't kick on unless I "reset" it by turning the summer switch off for 20 seconds then back on. Could this be caused by the "mother board" or possibly something simpler like a thermostat?

[cjlarsoni]

Countryboy, my Pulse21 does the same thing. Did you find out what was wrong?