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Tempstar DC90 pilot light or burner keeps going out. The furnace will run continuously. Even if I turn heat off at the thermostat. I have to kill power at the panel box to get it to shut off. Then I've been pushing the reset button near the ignitor and when I turn everything back on it runs fine for a while until some point where the burner in the Oval window at the top doesn't light again and the furnace runs contouring again.

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The reset button near the ignitor is a high temperature limit safety switch. When the furnace gets too hot and the manual reset limit switch is tripped, it most likely goes into a 'safe' mode where the gas control is locked out electronically and the blower is made to run continuously to rid the heat exchanger of the excessive heat. This will continue until the reset is pushed and the power is cycled off. It will remain an endless cycle unless the reason for the overtemperature condition is not corrected.

Your furnace 'temperature rise' is getting too high due to a lack of air across the heat exchanger for whatever reason. Some of those reasons could be a restricted air filter or a blower motor that's cycling improperly on its internal winding thermostat. You could also have a dirty air conditioner 'A' coil (evaporator) on top of the furnace restricting the air flow. Nevertheless, you are going to have to have it serviced by a reputable service company's technician to correct what's wrong.

Posted on Nov 30, 2014

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Posted on Jan 02, 2017

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SOURCE: Goodman Furnace Lights But Won't Continue to Run

The flame sensor is dirty. You can not see the build up on the sensor but enough build up will change the resistance and the furnace thinks there is no flame.

To clean the sensor, first you need to locate it. it will be a sensor located in the path of one of the flames. Once you locate the sensor, open the bottom panel to turn"off" the furnce. After the panel is removed, unscrew the sensor from the frame above the jets. Use a clean rag and gently wipe the sensor several times. Place back in the cut out and close the lower panel.

The furnace should cycle on and the flame stay on for the normal cycle.

Posted on Jan 18, 2009

  • 1 Answer

SOURCE: tempstar dc90 furnace will not light

Possible solution would be to push the reset button if you haven't already. I have had to do it twice on my dc90 in the last week.

If you look at the glass where you can see the combustion chamber, the glass is oval, follow the long axis of the oval toward the 'top' of the ignition chamber (my unit is laying down, with the blower on the west end and the combustion chamber on the east, as I am facing south). On top of the chamber are two protected spade clips. In between them is the reset. Make sure that the unit is off, press the button, and fire it back up.

Posted on Feb 20, 2009

  • 767 Answers

SOURCE: carrier super saver furnace keeps going on and off

Sounds like the flame sensor is dirty or bad. This sits in the burner flame when the burners are running. This usually has a single white wire connected to the back of it.

Posted on Jan 03, 2010

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A few questions for you. If the thermostat is satisfied as in turned below room temp, does the blower shut off. Are the filters clean? Furnaces have a limit control that governs how hot the heat exchanger runs. If the limit switch opens for some reason the fan or blower will continue to run until the limit switch closes. So dirty filters? A very dirty blower wheel? A blower motor that is not coming up to speed, Could just be a bad limit switch that is opening up at a lower temperature than it should. I would also check the pressure switch sensing tube. The end could be blocked with deposits

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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).

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1 Answer

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Check the air filter.
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).

Feb 26, 2010 | Goodman Heating & Cooling

1 Answer

Hi i hope you can help. I have a high effeciency furnace and the burners keep turning off.


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).

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1 Answer

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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).

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