HVAC BOTL's/ SOTL's - Furnace Issue

[earnold25]

Last time I had an HVAC issue, I got tons of help from here. Well, another issue has reared its head and I'm asking for help once again

I'm having an ignition issue with my gas furnace. Inducer fan kicks on, pressure switch hose / nipple isn't clogged, igniter glows (new igniter, just replaced it), than turns off. Igniters glows a total of 3 times, than system goes into lockout mode. Control board has a LED error code of one flash. Meaning ignition failure (manual says to check gas flow, gas pressure, gas valve, and flame sensor)

I sanded the flame sensor, it was slightly carbonized, but not terrible looking. Replaced it, issue still occurs.

Gas flow is turned on, I haven't messed with gas pressure, as it worked fine before.

Any testing I can do with the gas valve? I ordered a replacement flame sensor just in case. They're a good replacement to have around anyway I hear.

Oh, also testing voltage to the flame sensor, and it appears to not be an issue.

Any other ideas / things I can test before calling for service?

 

[gui_tarzan]

I don't know if this will help or not but in our other house we had a problem with the furnace not starting up. I paid $150 for a tech to look at it on Christmas Eve (no heat at all!) and it worked fine for about a week after he cleaned a bunch of stuff. After a few days of it working, not working, working, I started looking things over and saw some voltage numbers on the ignition module. So I checked it and there was no power on the side that kicks the gas valve open so the igniter wasn't lighting anything and would shut off! So for another $200 I could get the valve online. But I figured I'd open it up and look inside anyway just to see what was in there. Turns out there were a couple of bad solder joints and after I resoldered it it worked as normal and has since. I could have saved myself $150 if I had known to look there first.

 

[tuffy]

You said the igniter glows but no flame starts?

It sounds like a gas issue. Are you sure you are getting gas to the valve? Did you shut the gas to the furnace off earlier this year when you were trouble shooting the A/C?

Typically with a bad flame sensor, you will still get ignition. It will only last about 5 seconds before it shuts off because the flame sensor isn't detecting heat (usually because of the buildup on it).

Are you hearing the gas valve cycle on and gas coming out of the manifold? Have you had your gas shut off at any time since you used the furnace last? I am wondering if you have air in the system that is getting purged each time the furnace cycles.

 

[earnold25]

You said the igniter glows but no flame starts?

It sounds like a gas issue. Are you sure you are getting gas to the valve? Did you shut the gas to the furnace off earlier this year when you were trouble shooting the A/C?

Typically with a bad flame sensor, you will still get ignition. It will only last about 5 seconds before it shuts off because the flame sensor isn't detecting heat (usually because of the buildup on it).

Are you hearing the gas valve cycle on and gas coming out of the manifold? Have you had your gas shut off at any time since you used the furnace last? I am wondering if you have air in the system that is getting purged each time the furnace cycles.

correct, no gas hissing / no flame. i'm sure gas flow is ok to the unit, it is in the off position. I have a gas dryer basically off the same junction that is operating normally.

it appears that whatever tells the gas valve to open isn't doing its job. that or something is wrong with the gas valve?

 

[N2Advnture]

What the make/model? I know that there are a few manufacturers (quietcomfort or comfort master, something like that) that have issues with their control board that create this same issue.

I hope this helps
~Mark

 

[earnold25]

its a kenmoore, which i think is a rebranded something else. The control board is very similar to this

 

[earnold25]

now I have intermittent heat. I'd say 2 out of 5 times, everything works normally. The other 3 times it goes into lockout mode. Same issue, ignitor glows, no gas is ever delivered.

 

[N2Advnture]

I did some searching because I had a similar problem with my old house but couldn't remember the cause (I think my problem was a board problem).

I hope these help

~Mark

Question
My gas furnace, a Janitrol Model #GMP075-4, gives me a 1 blink code. Ignition failure. I have already sanded the flame sensor, but after the unit fires up for about 1-2 minutes, the flame kicks off and the ignitor comes on and glows orange 3 times before it goes in lock out. The flame never comes on again. Three other things listed as potential problems other than the Flame Sensor. Gas Flow, Gas Pressure and/or Gas Valve. I have someone coming to the house tomorrow and the diagnostic fee alone is $92.00. What do you think the problem is and what would we expect to pay for the repairs? I have seen some ridiculous cost differences for the same part. Example from $10.00 for the flame sensor to as much as $129.00. I think a crime is being committed here. What can I do?

Answer
it sounds like a defective flame sensor.
ensure that the pilot flame sits on the sensor to ensure accurate detection

if you are machanical you can perhaps change the sensor yourself
or get your quotes and pick the middle lower ones.

 

[N2Advnture]

Also, found this:

The problem could be the safety switch that detects the flue draft pressure is
stuck OFF and so prevents the gas valve from opening.

 

[jwintosh]

head west young man! no furnace problems here!!

 

[dpricenator]

head west young man! no furnace problems here!!

LOL:glassesgr

 

[earnold25]

head west young man! no furnace problems here!!

true enough...but than i have property value prices to worry about as well as left coast politics

 

[earnold25]

ok all. just to keep you updated on my status i ordered a replacement flame sensor, just in case. I'm thinking its the gas valve though.

i checked voltage on the probes that connect to the gas valve's terminals and got around 24 volts, so it looks like its receiving voltage, just not opening up to allow gas flow.

sooooo, who do i contact about removal / installation of gas pipes? plumber or hvac guy?

 

[earnold25]

Also, found this:

I did some searching because I had a similar problem with my old house but couldn't remember the cause (I think my problem was a board problem).

I hope these help

~Mark

sorry Mark. I didn't see your replies. Thanks!

I have tested the flame sensor already, as well as sanded it down. I did order a replacement just to be sure, but it looks like its note the issue. Its getting voltage from the board and everything looks normal there.

Also, doesn't appear to the be pressure switch, as the ignitor wouldn't turn on if the pressure switch didn't engage. To be sure i checked to see if there was any debris in the tube or pressure switches nipple. both were clear.