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Nordyne CMF 80 Won't Stay Lit

2766 Views 3 Replies 4 Participants Last post by  Marty S.
Came home from work Thursday night to a cold house. After trouble shooting and watching YouTube videos I figured out that it might be the ignitor. I took the part out and sure enough the ceramic coil was cracked. I found a compatible part at Grainger, listed the model of coil on the back of the package to the broken one in hand and installed last night. Once back in place I hear the unit begin the warm up cycle, hear the ignitor light and gas start but within a few seconds I hear it cut out. The longest I've gotten it to run is a minute, something keeps tripping it out. I am getting 3 flashes which is telling me that there might be a "false flame" but really unsure of where to go from here. Any help would be appreciated. Now that it's the weekend before Christmas I doubt I am going to find any "good" part stores open and really can't afford to have a plumber here to check it out. Not sure if the igniter is the wrong one, where I would find the right one, or if it's the gas valve or something else. I appreciate any advice, can take pics and post any more info if needed.
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I dont know your particular furnace, but if you initiate call for heat with the burner box open do all of the burners light and burn a nice blue flame? If they do, I would clean the flame sensor lightly with fine steel wool, put it back and initiate the ignition sequence. If you have the type where the ignitor and flame sensor are close together, check the flame hood to make sure it has not warped, and make sure the flame sensor is in the flame envelope.

If Yuri or the other HVAC Pros come on they will be able to tell you more accurately, as they know the particulars to most every brand of furnace out there.

Meanwhile, try what I said above.
False flame is extremely rare, make sure you read the code properly. May be low flame signal. Then you need to clean the flame sensor. It sits in front of one of the burners and has white porcelain holder and looks like a nail, clean it with clean steel wool or fine emory paper.


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If it is a false flame code with no actual flame then that means (1) the flame sensor or flame sensor wire are touching ground or (2) the control board has failed and giving false error codes. Double check the legand as yuri said.
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