I have a Goodman natural gas heater, model GPM 100-4, serial # 9301018075. When I turn the heater on the burners will kick on for a few seconds and then kick back off. It repeats this process three times and then shuts down and I have to turn the switch off and then back on to reset it. It then repeats the same process three more time. Once I do this process 4 to 6 times the heater will kick on and run perfectly. I guess the burners burning a few seconds at a time eventually warm up the heater cabinet and it runs. I can also get a hair dryer and blow warm air into the heater cabinet for about a minute and the heater will run perfectly. The problem is when the heater cabinet is cold it won't run. This has been going on for about three years now. The local HVAC repair shop has replaced the circuit board twice, replaced the burner flame sensor twice and cleaned it numerous times and also replaced a small diaphragm connected to the purge blower. None of this has fixed the problem. The local repair shop is stumped. Has anyone had this problem before? Any help would be greatly appreciated. Ronny