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Janitrol GUPS075-3 Furnace burners will not stay lit

I have a Janitrol GUPS075-3 furnace (but the circuits match the wiring diagram for a GUPI model in my book). Induced Draft fan turns on, pilot lights, main blower turns on, main burners ignite and burn for 5 seconds then shut off. Pilot remains lit and the pilot ignitor keeps sparking continuously for several minutes with the pilot flame lit. Then eventually the ingitor turns off and pilot goes out. Main blower shuts off after a while. Induced draft fan keeps running all the time no matter what. Whole cycle repeats indefinitely every 5+ minutes. I can get the burners to stay lit if I grip the main valve with my hand and hold onto it while the cycle starts. Any ideas?

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The first thing I would do is make sure the flame sensor is clean, this is a metal rod immersed in the burner flame on the opposite side of the igniter. If too much oxidation builds up on it, it will not allow the burner to stay lit. To clean, just turn off furnace and remove flame sensor and clean with steel wool and then reinstall. If this does not solve the problem there may be a problem with the gas valve.

Posted on Nov 08, 2012

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Posted on Jan 02, 2017

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  • 18 Answers

SOURCE: pilot lights but no main burner

Is there a way to check for gas pressure even if just a slight loosened connection to hear it then quickly re-tightened. Otherwise the main valve is not working as it should and will need to be serviced or replaced. Thats all i got.

Posted on Dec 07, 2011

  • 39 Answers

SOURCE: I have a Rheem Criterion II Gas Furnace that has

Turn off the power to furnace.
on the last burner to light there is a small metal rod in front of the burner. This is a safety called the flame sensor. It is dirty. Unscrew it from the bar ( 1 Screw) unplug the connector wire from it and clean it with steel wool. it will be kind of burnt. Plut back in place and turn on the furnace to cycle.

Posted on Apr 04, 2010

heatman101
  • 43501 Answers

SOURCE: I have a 90+ gas

Hi,
What you are describing would seem to indicate that the high limit switch tripped....

Check to see if there is a manual reset high limit in that heater...also recycle the power at hte circuit breaker to reset it from a lockout to see if the high limit is an auto reset...

If none of that works then the high limit may be bad or the circuit board is bad...

heatman101

Posted on Nov 25, 2010

  • 2 Answers

SOURCE: Williams 3003622 Wall Mounted 30,000 BTU The pilot

I'm having the same exact problem... At first we thought was the vent... but the way the flames goes out... it seems that there is "not enough oxygen" more than "blown out by the wind"... right after both main & pilot goes out, I can't even light any external flame inside the chamber... and it doesn't feel like the outside cold air coming in... it just feel like there is some sort of gas in the chamber that's so strong, it prevents flame... and the only thing I can think of is that it doesn't have enough oxygen, but too much natural gas, and flame can't sustain.

Posted on Dec 16, 2010

  • 1033 Answers

SOURCE: I have a Ducane MPGA100B4B gas furnace. The

Hello, sounds like the limit switch is opening on the furnace.Usually when a furnace goes off on its high limit is becuase the airflow is being restricted making the furnace overheat. a limit switch is there to protect the furnaace from overheating, most cuases are either dirt or the blower motor not running up to speed, anything that cuts down on the airflow will cause the high limt switch to open.

Posted on Feb 24, 2011

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1 Answer

Suddenly not working im not sure if there even is a pilot to be lit


Goodman have troubleshooting idiot lights on the board. Look for flashes and count em.
The flash explanations are printed on the backside of the blower cover on most models.
A sampling of various failure codes on a furnace:

Read one LED flash that stays on continuously to mean your furnace has no signal coming from the thermostat and will not operate. Turn the power off and check the thermostat for improper settings or connections.

Interpret one LED flash that blinks on and off to mean your furnace has locked out because it could not ignite after three tries, and must be reset. Interrupt power to your furnace for 20 seconds or lower the thermostat so your furnace does not try to heat, then reset the thermostat to the previous setting. After one hour of lockout, your furnace will automatically reset itself and try to operate as usual.

Decipher two LED flashes to mean the draft blower is not working, or your furnace has a short in the pressure switch circuit. Turn off the furnace power and repair a short or replace the pressure switch.


Read three LED flashes to mean your furnace has an open pressure switch circuit or it has an induced draft blower operating. Check the pressure switch hose of your furnace for blocks or an improper connection. Also, look for blockages in the flue, and tighten any loose wiring.

Translate four LED flashes to mean your furnace has a primary limit circuit open, possibly from loose wiring or blocked filters. Check and clean filters, tighten wiring and check the flue for blockages.

Interpret five LED flashes to mean your furnace senses a flame without a call for heat. This could be from a gas valve closing slowly or a burner flame lingering.



Read seven LED flashes as a warning of a low flame sense microamp signal. This could happen with a coated flame sensor or a lazy flame from poor gas pressure. Turn off the power and adjust the gas pressure according to the information on the rating plate.



See eight LED flashes as meaning an igniter circuit problem due to a bad igniter or an igniter connected improperly. Replace the bad igniter or check the ground wiring, making necessary corrections.



Decipher nine LED flashes to mean the high-stage pressure switch circuit will not close during a high-stage-induced draft blower operation. Your furnace may have a pinched or blocked pressure switch hose, a blocked flue or loose wiring.

Read continuous flashing on the LED to mean your furnace has a reversed polarity of 115 volts. Turn off the power and correct the wiring polarity after reviewing the wiring diagram.

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Rheem 90+ NG Furnace. When furnace starts, draft inducer starts, ignitor glows and gas ignites. Burners stay lit for 10 seconds or so, then the flame reduces for a few seconds then goes out. Main blower...


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1 Answer

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