Keeprite NG furnace code "fail to ignite"

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4spdragtop

4spdragtop

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Hey all wife went to turn NG furnace on, no go. Led flashes code "fail to ignite/flame sense lost while running"
Pulled both panels off and can see igniter heat up BUT is it hot enough?
I would assume it is similar to our NG oven/stove that igniter has to get to a certain temp before the gas valve opens?
I'm thinking it's either igniter not hot enuf or gas control valve (Honeywell)
Keeprite 2stage hi-eff.
Thanks
Steve
 
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If it never lights at all, I'm betting on the gas valve myself. Still a possibility it's the pressure switch depending on how good the diagnostics are, but I really doubt it.

Also check the flame sensor for being open just to be sure.

It should be somewhat like inducer or powered exhaust turns on -> ignitor starts sparking or glowing -> gas valve opens -> flame lights -> checks flame with flame sensor -> burns for a time -> blower kicks on
 
If the igniter is glowing, it is likely working.

There is a flame sensor that is usually on the opposite side from the igniter. it is just a little metal rod with a wire attached to it. Pull it out and clean it with a piece or sandpaper or steel wool. That fixes it a lot of the time.

How the electronic furnace work is pretty simple, but not very obvious.

1. The exhaust flue fan turns on ( not the blower motor).
2. A vacuum sensor in the flue detects the vacuum from the exhaust fan and closes.
3. The igniter turns on and glows.
4. The gas turns on and the furnace lights.
5. The control board starts looking for the flame sensor signal. If it doesn’t detect a flame, it turns off the gas after several seconds.
6. If the furnace didn’t stay running it will repeat the sequence every few minutes a few times. If it does it enough times you will need to cycle power to the furnace.

Once you understand how it works, it isn’t too hard to troubleshoot.

Don’t touch the igniter, they break really easy.
 
so intial blower kicks in, igniter lights, then that repeats a couple times. Control valve appears to clicks, but that's it? Dont see hear smell gas.
Gonna pull flame sensor and clean.
Thanks
 
Sounds like you have either a bad gas valve or blocked gas orifices (little green spiders can crawl in the orifices and make a nest blocking gas flow - seen it many times in my 22 years in HVAC)
Also, make sure you have gas to the furnace.
 
If the ignitor heats up, it is surely OK. Flame sense is not active for a few seconds of flame.

The sequence, depending on the type of furncace:

1...Call for heat activates the control board/ ignition module, certain safety switches must be closed, AKA over temp, plugged vent, vent spill, etc.

2...Module fires up draft blower for a certain time, then commands igniter to come on. It is timed for so many seconds, and you should hear a "click" when the gas valve opens.

3...When the gas valve is commanded open, the burner should ignite. There is several seconds delay to allow the burner to stabilize, and to obtain a flame signal

4....The flame detector works like this: The flame rod/ flame detector works by what is called "flame rectification."

The rod (may be the ignitor itself, or a separate rod) is fed a fairly high voltage, around 100V AC, current limited signal, and when a good solid flame is present, the flame itself rectifies the AC similar to a crystal radio, and a circuit in the ignition module, detects a tiny DC current, down in just 1 or more microamps.

I would study the circuit carefully to see if there are any safety switches in series with the gas valve, and then rig a meter "backprobe" into the gas valve solenoid (s). There are many times two valves for safety. After the igniter has been on you should read 24AC at the gas valve terminals, and if the solenoids are working, should hear and feel a "click" as they activate.

ALSO if the solenoids seem OK, CHECK INCOMING GAS PRESSURE. Or do you? have another working appliance, such as range, dryer, etc?
 
Steve post up the brand/ model, and see if you can find a link to the service/ schematic.

Also most of these have a "lockout" AKA it will cycle and try to light 3 or 4 trys, then lockout. You have to turn off power a few seconds and back on for it to re-try.
 
1969reddart said:
Sounds like you have either a bad gas valve or blocked gas orifices (little green spiders can crawl in the orifices and make a nest blocking gas flow - seen it many times in my 22 years in HVAC)
Also, make sure you have gas to the furnace.
Click to expand...
That is interesting. In the years I was in HVAC/R service, I have never once seen fully plugged orifices
 
4spdragtop said:
so intial blower kicks in, igniter lights, then that repeats a couple times. Control valve appears to clicks, but that's it? Dont see hear smell gas.
Gonna pull flame sensor and clean.
Thanks
Click to expand...
I would not clean the sensor. Some of those combo sensor/ ignitors can get brittle and break easily. I would sure find and buy a spare ignitor
 
67Dart273 said:
That is interesting. In the years I was in HVAC/R service, I have never once seen fully plugged orifices
Click to expand...

Spiders nests in the main gas orifices may be a regional issue.

It was a problem in the Bay Area - California.
My wife also had recurring issues with this in her wall heaters in rural Arkansas.
 
Gas is turned on lol, dryer works, stove works bbq works. Maybe I'll sleep in the dryer?
Of course I removed the flame sensor and dropped the fn mount screw in behind "transition"...whatever the f that is.....:BangHead:
mcodecuda said:
Is your gas to the furnace turned on?
Click to expand...
 
4spdragtop said:
Gas is turned on lol, dryer works, stove works bbq works. Maybe I'll sleep in the dryer?
Of course I removed the flame sensor and dropped the fn mount screw in behind "transition"...whatever the f that is.....:BangHead:
Click to expand...
I was referring to the shutoff valve right at the furnace not the main gas shutoff.
 
67Dart273 said:
The sequence, depending on the type of furncace:

1...Call for heat activates the control board/ ignition module, certain safety switches must be closed, AKA over temp, plugged vent, vent spill, etc.

2...Module fires up draft blower for a certain time, then commands igniter to come on. It is timed for so many seconds, and you should hear a "click" when the gas valve opens.

3...When the gas valve is commanded open, the burner should ignite. There is several seconds delay to allow the burner to stabilize, and to obtain a flame signal
Click to expand...

It all depends on the furnace manufacturer and the Specs they gave the PCB supplier, but for the most part, this a good, rough approximation.

Your HSI is working fine, but I don't think the gas valve is getting energized (I don't hear it).

To the OP: Are you comfortable with a VOM, and/or do you know how to measure AC volts?

The Sequence of Operation above is a good start, but it's missing the pressure switches. On some models, the switch (or switches) has to make within a certain period of time, while on others it has to make, and then break, within a certain period of time. And if any of this doesn't happen correctly, the gas valve will never be energized, so....Would you be comfortable measuring the voltage on the gas valve as it tries to start? (24 VAC, nominal)

My point being, w/o the model and S/N of the unit, all anyone here can do is guess, but I've worked Technical Support long enough to know that the same board can have different programming in it, depending on the manufacturer.

If you can post a picture of the M/N and S/N of the furnace, as well as the numbers off the PCB, I can dig-up the schematics, Sequence of Operation, and the Fault Codes, and we can work through this step-by-step. This is what I've done for a living for 30+ years, and I'm in the office right now.

(Or, what the hell! Give me a call at the office. Shoot me a PM for the number, if you think it will help. But I'll still need the info off the furnace.)

I may not be worth a damn on Mopars, but this "stuff" is right up my alley.

Jim
 
^^Won't items as you mentioned show up in the error?^^ But without specific model, I can't get closer
 
Steve I already asked, we need the model no. and if you can find one, a link to the booklet/ service/ install manual. I found one online, no idea if it is the correct one.
 
67Dart273 said:
^Won't items as you mentioned show up in the error?^^ But without specific model, I can't get closer
Click to expand...

67Dart273 said:
Steve I already asked, we need the model no. and if you can find one, a link to the booklet/ service/ install manual. I found one online, no idea if it is the correct one.
Click to expand...

Sounds like you and I are on the same page.
 
To 67Dart273:

There's a quick shot of the AGA sticker near the 1:05 mark of the video, but I can't make out anything. May be the video, or may be my el-cheapo monitors here at work.

Jim
 
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Sorry guys, missed some replies and I hit "eject" button as family was over for Spanksgiving.
Model C9MVX080J20A1
S/N A095060469
MFG DEC 2009
I have owner and install manual.
**edit** drop the "C" at beginning of Model #
 
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