[Cs641]

Thank you so much for the help!!! I understand that this is an economy brand furnace. I will be replacing it come summertime, but for right now I just need some heat.

Yes, tin pipe chimney shared with water heater and clear to the sky.

Brand new air pressure switch and hose.

Thermostat is properly wired calling for heat.

Rollout switches have been verified not to be the culprit. Same result after (temporarily) bypassing.

After the initial ignition the board wants to kill the flame after about 6 seconds. If I apply a 24 V jumper to the gas valve after the flame has already ignited the board is unable to shut off the valve(I can hear it try), flame stays lit and several seconds later the blower is instructed to warm the home. As soon as I pulled the 24 V from the gas valve, the flame quits and the board tries to relight. It will relight but will not stay on past 6 seconds.

I do not own a manometer but I’m probably going to pick one up.

 

[Cs641]

Copy that. I will try your trick on the air switch.

 

[Cs641]

Did the jumper trick, same exact results.

 

[Cs641]

All rollout switches are good. Same results after bypassing.

if I let the furnace try and do three ignition cycles, I do get an error code on the board for failed ignition. Even though there is flame present for the first six seconds.

Going to try your recommendation on PS1 to gas valve power.

 

[Cs641]

Here’s the results:

Tested for micro volts using the 300 MV scale on my meter. Showing a constant fluctuation between 0.1&0.2 as well as the polarity. No fluctuation or change when there is flame. I do have the proper meter coming. Working with what I have for right now.



When I did the bypass, you suggested the furnace kept the gas valve open and wanted to run a full cycle.


I am going to post a picture of the rollout switches, I have., I am only seeing three of them. Two mounted in a horizontal position directly over the burners, and a third mounted in what I believe is the heat exchanger.

 

[Cs641]

 

[Cs641]

The peach colored wires on the rollout switches over the burners go directly back to the board.

The orange colored wires for the limit switch also go direct back to the board.

There is also the wiring for the draft inducer sensor, which also goes directly back to the board.

I am seeing a bit of difference between the manual and the way it’s built.

 

[Cs641]

I did want to add that when I do the bypass the flame will quit as soon as I un-bypass it.

 

[Cs641]

I am wondering if the control board is bad. I guess the only way to tell is by seeing the micro volts with a proper meter?

Bypassing the air switch yields the same results.

Bypassing both of the thermal switches yields the same results.

With that being said I think it’s safe to say the air switch and thermal switches have been eliminated.

 

[Cs641]

Copy that. Once the right meter gets here I’ll let you know how many micro amps we have

 

[Cs641]

Got my new meter, a Klein CL320. Immediately upon ignition I see 3.7 Microamps then it flutters down to about 1.9 then up to 2.3 until the board kills the gas valve signal. There’s probably two seconds, maybe three between hitting 1.9 and leveling out at 2.3. By the time the gas valve signal is killed it is holding steady at 2.3.

Bad board?

 

[Cs641]

1.9 is low enough to trip it. Take out the flame rod, use 220 sand paper to clean the rod, make sure it is in the flame good, not too far off to the side.

That’s the thing, flame rod has been polished to perfection and replaced 3x now.

I tried adjusting the flame rod while the furnace was burning with the safety bypass to see if I could get a higher number and I don’t, it tops out at 2.3.

would cleaning the burner or adjusting the gas pressure get a higher reading?

 

[Cs641]

Ok. Today’s progress:

Burners are cleaned.

Flame sensor reading a constant minimum of 2.6

Same results

 

[Cs641]

Copy that. Got a new one on order

 

[Cs641]

Replaced the board with a genuine Goodman board. Furnace runs like brand new.

THANK YOU for the help!!!