I cleaned the flame sensor and checked the filter. Furnace works fine until it reaches the set temperture then shuts off for a second then starts up and runs for about 3 min. It will cycle like this for 15 min or so then shut off.
Replace the flame sensor
SOURCE: flame rollout sensor keeps tripping
The flame rollout sensor is a rather important safety feature that ideally only trips when there's an overtemperture outside of the combustion chamber. I'd encourage you to get a better quality tech in ASAP to check for a cracked heat exchanger, gas overpressure, restricted airflow (changed the filter lately?), maybe a blocked condensate drain if this is a high efficiency furnace. If the sensor was replaced and it's still tripping, you've got a potentially dangerous overheating issue that you don't want to try to bypass.
SOURCE: FURNACE COMES ON AND SHUTS DOWN WITHIN 15 SECONDS
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). When all else fails, check the ground connection for corrosion.
SOURCE: Amana Air Command 80 SSE gas furnace will not stay running
In the path of the flame on the last burner that starts, there will be a small rod. That rod is the flame sensor. Take a scrub pad and polish it. Also check the electrical connection that goes back to the circuit board. Disconnect any ground wire from the circuit board to furnace cabinet, sand it and replace it.
SOURCE: I have a goodman gmpn 100-4 furnace. It will not
Clean the flame sensor with a scotch brite pad....gently and replace it.
SOURCE: Nordyne furnace. The furnace comes on, flame
Hello. The first thing you can do is check the flame sensor, this is a small metal rod on the opposite side of the ignitor, Turn off power to the unit remove flame sensor and clean it with some steel wool. Also check the flame sensor to make sure there are no cracks in the base of it, if so then replace the flame sensor. If you have checked the flame sensor and the problem still continues you might have a problem with the unit not being grounded properly, you should have a ground wire coming from the main electrical panel to the furnace. If the ground wire is there and problem continues the control board should be replaced. I hope this helps.
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