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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Burner lights everything looks normal flame goes out after a

Customer Question

burner lights everything looks normal flame goes out after a few seconds goes through the cycle 3 times and shuts off code comes up ignition failure what could it be changed flame sencor still does the same thing
Submitted: 1 year ago.
Category: HVAC
Expert:  Scott replied 1 year ago.


My name is ***** ***** your Coleman furnace a Manufactured home type or the upflow basement type?

Customer: replied 1 year ago.
moble home
Expert:  Scott replied 1 year ago.

Ok could be a poor ground for the furnace, however depending on your area it could be a spider web or silk worm nest in the main gas orifice, this will sometimes let enough gas trough the web to ignite but not enough for the flame to develop fully and make good solid contact between the flame rod and the burner head itself. Do you know how to check the burner orifice?

Customer: replied 1 year ago.
no how would i know it has a bad ground
Expert:  Scott replied 1 year ago.

Tell me when the last time the furnace worked normally.

there should be three wires coming in the side of the furnace one black one white nd one bare copper the copper wire should be wire connected to the furnace cabinet some how could go to a green ground screw could go to a green wire screwed to the cabinet be sure its connected tight.

Customer: replied 1 year ago.
last year
Customer: replied 1 year ago.
checked the ground looks good
Expert:  Scott replied 1 year ago.

The Main burner orifice is connected to the gas manifold valve, shut the gas off, remove the 2 5/16" head screws from the valve bracket and slide the orifice tube out of the furnace burner you may have remove this when you changed the flame sensor. the orifice is the brass nut on the end of the pipe, look down into it with a flashlight be sure its clear if you see a web remove it with a tooth pick or pipe cleaner sometimes you have to remove the orifice from the tube it is 1/2" a box end wrench works best

Another thought that comes to mind is that the male female connector that is above the flame sensor may be broken not making contact.

Expert:  Scott replied 1 year ago.

If you have a multi meter that reads micro amps DC when can test the flame circuit to be sure the board is sending out the 3.5-4 ua signal to sense the flame. There is the possibility that the board is bad but you should examine it carefully for corrosion or burn spots. because it is and expensive part no need to change it without a good test.

Customer: replied 1 year ago.
you talk about a male female connector above the flame sensor the only thing above the flame sensor is steel rod with a disc at the end it is connected to the burner