On a call for heat, the 24 volt thermostat sends a signal to the control module. The control module will indicate a call for heat with a light on the control either blinking or remain solid depending upon model. The inducer (exhaust) blower will purge all gasses from the furnace and pressurize a pressure switch. Once the pressure switch tells the module to continue, the electronic ignition will energize and send 120 volts to the igniter. The igniter will glow and you will be able to see it if viewed thru the small inspection port. Once the igniter gets hot enough, it sends a signal to the module opening up the gas valve (24 volts). Either a pilot will come on or the burner tube will ignite then spread the flame to all burners. Lastly a safety sensor will be looking for a certain temperature within a few seconds and the furnace will continue to operate and the room air blower will turn on in a minute or two.
What could go wrong? The unit will not run if there is no signal from the thermostat (bad thermostat or broken wire), the control module does not sense a signal from the thermostat (bad control), the inducer does not energize (bad motor), the pressure switch does not close (blocked vent piping, bad switch, plugged condensate hose), the igniter does not energize (bad control, bad igniter), the gas valve does not open or there is no gas (bad gas valve, broken wire, no gas), the pilot does not light (dirty pilot), the burner does not light (bad burner, plugged orifice, not enough combustion air), the flame does not spread to each burner (bad flame spreader, dirty flame spreader, more bad burners), the flame safety sensor does not detect flame (dirty or bad flame spreader, bad flame sensor, broken wire, bad control), or the room air blower does not energize (bad fan motor, bad control).
SOURCE: I have a goodman 6mnte080-4. Home had power
Check out the green wire going to the gas valve for proper ground,and also check all wires for good connections......... for the intermitting start / stopping and sand the fame sensor pin, this should do the trick.
SOURCE: RHEEM RGLE-10EQAGS Gas Furnace - Intermitent.
The sequence is Igniter comes on, valve comes on, flame sensor senses flame. If no flame is sensed after 3 tries, a lockout occurs. If you have a volt meter, check for 24-27 Volts AC coming to the gas valve, if your getting voltage to the valve but no gas, your gas valve is defective. It could be a intermittent problem, no matter, still a bad valve. if no voltage to valve, defective circuit board.
SOURCE: I have had to replace the hot surface ignitor
I would check the grounding from the circuit board to cabinet, the ground coming in to the power of the furnace as well as the ground lug in your panel box. These furnaces are polarity specific and the wrong polarity or a loose ground will effect the longevity of the ignitor. Always buy a spare.
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Does the draft inducer start up? Greg Sunsetmech
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