I have a Lennox gas furnace heater and the model is G16Q4X. This model has Intermittent pilot ignition system. On top of the Gas valve, the Johnson's control module - "Ignition control with Lockout" model G60QHL-1 with input 25 volts.
When I turn on the heater, I see the pilot flame comes on and stays fraction of a second. It goes on few more times and finally the burners catch fire. The burners burn about 10 to 15 seconds and the flame dies. After that the pilot retries and continues. In the second time around the burners do not catch fire. I took the pilot after removing to a parts store and he told me there is nothing wrong with the pilot and flame sensor which is single unit. The store guy tells me that the contol may be the problem. I am really confused with this. The control has just electrical parts with a transformer and a small pc board. Right underneath this controller, there is gas valve with two solenoid type of things. I do not know where is the problem. Do I need to change controller or the Gas valve or just the flame sensor. I would appreciate your help.