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Coleman DGAH077BBSA flame sensor problem

Posted: Fri Oct 12, 2007 1:18 pm
by jake1688
I have the above model furnace. Its only 3 years old, but I am having problems with it firing up and blowing cold air. I've read enough of the online info to figure its probably the flame sensor, but I can't figure out where it is located. I have no problem doing DIY projects to clean it off, but I can't find any site that shows where it is. I can email a photo to anyone that can help. My biggest fear is taking apart something I can't get back together or that shouldn't come apart. Thanks for any help.

RE: Coleman DGAH077BBSA flame sensor problem

Posted: Fri Oct 12, 2007 4:41 pm
by Robert
Hi,

It's beside the burner and ignitor. This is not a DIY task for everyone, but can be done.


Do not touch ignitor or flame sensor with your hands/fingers.


Clean the flame sensor with steel wool gently.


Look at flame sensor for cracks around the ceramic shroud.


Has it just started this or been doing it from beginning at install ?



Take care and best wishes,
Robert

RE: Coleman DGAH077BBSA flame sensor problem

Posted: Fri Oct 12, 2007 5:25 pm
by jake1688
Its the first time this year I have started it up. I can find a circular plate with a little viewport in it. Its hard to explain but I'll try. The gas valve assembly is attached to the lower half of the circle. I unscrewed the plate that the gas valve is attached to, but the lower half of the plate comes off with only a small nozzle that goes into the actual burn chamber. It seems the circular plate is sealed. Do I need to pull this off to get to the sensor?

RE: Coleman DGAH077BBSA flame sensor problem

Posted: Fri Oct 12, 2007 9:16 pm
by Robert
Hi,

There are gaskets behind the plates and if damaged, will have to be replaced.

This is a pic of a burner assembly with a flame sensor:

http://www.mobilehomerepair.com/media/i ... 0-5851.jpg


It IS NOT yours, but one similar to show where flame sensor is located.



May be time to call a Tech to save a costly mistake or an injury.


Thanks,
Robert

RE: Coleman DGAH077BBSA flame sensor problem

Posted: Sat Oct 13, 2007 8:35 pm
by jake1688
Thanks for the pic, it helped totally. I found the flame sensor and cleaned it with steel wool, but it didn't make a difference. I still get the blue flame out of the unit I pulled out, but no warm air. Any other suggestions as to what I can do or what it could be? Thanks!

RE: Coleman DGAH077BBSA flame sensor problem

Posted: Sun Oct 14, 2007 2:09 am
by Robert
Hi,

IF the burner is igniting and you have a nice steady blue flame of proper size and blower is coming on, then check all ducts.


Other than that, it will take equipment and tools plus experience to test the cycle and firing process to determine reason for no heat.


Have you checked the burner orifice at gas valve for blockage by spider/web ?



Take care and best wishes,
Robert