no fire in the burner

[marc.ferdie]

I have a Tempstar furnace with model no. ntgm075ega3. When I turned it on, the fan works, exhaust fan also works but the burner does not fire. I checked the wires from the circuit board going to the gas valve.

Black wire has 24 volts AC
Orange and the blue wire does not have any volts or power in it. Is this normal?

I also checked the wires from gas valve to the ignitor.


3 Wires
only one of the 2 blue wires has 24 volts AC
the black one does not have any voltage. Is this also normal?

Please help me what to do next.

[Grady]

Look on the gas valve for the part #. Does it begin with SV?

[ecman51`]

Does the ignitor part of the sequence work or not? What kind is it?

Kind of hard to just go on color of wires without knowing what at least the abbreviations might be where the wires plug in, at each end.

And you also say you tested or checked this and that. We have no idea if you know the proper way to test. You really should say exactly what you tried to do, in some detail.

[SeattlePioneer]

I second the Noble ecman's request.

I'll also suggest that you take the cover off the burner compartment and carefully note the sequence of events that occur as the furnace operates. You'd probably have to repeat that several times before noticing what's happening in detail.

If you can report what you are seeing and hearing, we'll have a better chance of sorting out what is happening.

[marc.ferdie]

Thank you for your help.
the model no. of the gas valve is SV9501M2726 whereas the model no. of control board is ST9120C4057.

When I turned on the furnace, I observed the opened burner compartment for 5-10 minutes, there is no fire, no spark, nothing.

I wish I could give you the connection diagram to make things easier for you but it will still take more time at my end.

Due to the urgency of the situation, (negative 3 right now and were so cold) I decided to call the technician tomorrow. I just wish that the technician will not rob me with different fees and all that, coz I just lost my job.

Please accept my deepest gratitude for somehow helping me.
I love learning and solving problems like this. When I had the chance and $, I will enroll in a course relevant to this kind of profession.

More power to you guys.

[SeattlePioneer]

If absolutely nothing is happening, that suggests you don't have power to the furnace.

Check to be sure the circuit breaker at the breaker box is turned on, and any power switch next to the furnace. Check to be sure that the cover for the fan compartment is properly closed, since often there is a switch that must be depressed by the fan compartment cover before the furnace will operate.


You say that nothing works, but in your first post you say the inducer motor works. Does that motor work or not?

You say the fan motor works too. When?


Is there a furnace wiring diagram? Can you read any parts of it, such as tracing the 24 VAC?

[Grady]

When you were talking about two blue & one black wires to the ignitor I suspected a Smart Valve. Figure 14 of this pdf is a troubleshooting chart.
http://customer.honeywell.com/techli...it/69-1004.pdf

[marc.ferdie]

Hi,
It turned out that the furnace shuts down by itself because there is a problem in the heat exchanger which is not visible to me unless a special intrument is used to view what is inside. The way I understand is that the fire in the chamber backs up because the heat exchanger is broken. As a result the furnace shut itself automatically. A replacement of the heat exchanger is on its way.

Thank you all for your help.