Hi guys

Furnace : whisperheat with ignition box close and open
The furnace carries ignition model and spark sensor pilot.
On G/V you can see mp mp/mv mv which are all connected to the igniton module and grnd connected to the furnace .
Now the problem :
When you call for heat ,the furnace blower keeps running and you can see the sparks and ball of fire but the burners do not fire up and then after few seconds the spark stops and the blower still keeps running
Now my question , how would you give it a thorough check to make sure that the ignition module is working properly and how would you measure the ignition voltage to ensure that the required voltage reaches to ignitor .
Checked out all the limits and reset them however still the blower keeps going and no burners fire up
Any advice will be appreciated

Without a Exact model number this should get you the info you need.

http://www.cozyparts.com/Lennox-Parts/forum/Lennox_service_manual/Furnaces/G20_01-01-2003.pdf

If the pilot lights (but no main burner operation) and the blower starts, check the gas control MV-MV/PV for 24 volts. If present, gas control is bad. If not, ignition module is bad. Blower on-delay signal from ignition module is sent to blower control board once pilot is proven.