Lennox Pulse 21 Question
The ignition control module was just replace but the furnace still doesnt run, it just continually cycles and the fan continually runs.
Also the air flapper valve was cleaned.
Could this be a problem with the spark plug or heat sensor?
The Lennox Pulse is a unique unit that requires a skilled mechanic.
It should also have a professional perform a heat exchanger test on it to make sure the integrity of the heat exchanger is good.
It could be anything but nothing that you can fix without the knowledge to do so.
spark plug only fires for about 7 seconds at beginning of cycle and flame sensor only proves it is firing,
normally neither one of these parts will cause your problem.
find someone trained on the pulse and have them check it out.