I have a Goodman furnace GDS80703AXBA, the unit has 3 years and it's located in a closet. I've started to have problems last year with the heater, especially during the morning. The fan is on but the heater is off, with the LED blinking one. Most of the time I turned the thermostat off and unplug the cable of the outlet to reset the unit. Most of the time solve the problem but I have to do it every morning. I've just replaced the heat sensor,the igniter and clean the gas orificies. Any help?