Not always, but often the furnace continue blowing cold air after blowing heat. It may blow cold air for more than 30 minutes. Under this conditions I also see the error code (8 red flashed) "Ignition lockout due to recycles".
Is there anything that I can easily adjust/a part to replace? Here is how the furnace looks: Adding observed sequence. After a day thermostat on OFF, I switched it to heat and the very first sequence was fine - inducer blower first, then bright orange ignition, then click and steady blue gas flame, then blower fan, then after several minutes all off (and the diagnostic LED slow green "all normal"). However the second sequence, several minutes after the first sequence, revealed the problem:
- Thermostat is on heat
- Inducer blower ON (diagnostics LED slow yellow)
- Bright orange ignition light ON
- A click, blue flame ON, but after a few seconds it's OFF
- The steps #3 and #4 repeat about four or five times
- Orange ignition light OFF, inducer fan OFF, blower fan ON, the diagnostic LED 8 red flash "Ignition lockout due to recycles". Blows continuously for until I turn the furnace power off.