Good Afternoon,

I have been trying to fix my Goodman for a few weeks now. It is a model GKS90904CX (propane). I know one flash means a lockout. When I turn the thermostat on and off it will reset the furnace and allow it to run until it reaches temperature. This is an intermittent issue, could work for 2 days, and then happen again.

I have cleaned and then replaced the flame sensor. The ignitor lights up perfect, and I had a spare that I put in just in case and that did not fix it. I read that the circuit board could be a common cause so I replaced that (wasn't expensive), but I am still have a problem. I also upgraded the thermostats, but the problem happened with the old and new thermostats.

When the furnace clicks on, the blower turns on, the ignitor lights, the gas ignites, and then after a few seconds it stops. I tested the pressure switch and it makes the clicking sound, and there is no water in the line. What else could it be? I live in the Northeast and would be looking at $300 for someone to show up, so any help that you could give I would appreciate it! I have a multimeter, but I am not too familiar how to use it.

Thanks!

 

Welcome to the forums,

Furnaces are not an install and forget appliance until they break down.
They require mandatory cleaning.

You need to get the fault code when the furnace fails. It will fail three times before going into lockout,

 

Hi. After the three attempts, I get a single flash fault code.

 

What code do you get after the first attempt ?
It should flash the problem code when it happens and then after three times show the lockout code.

 

Good Evening. I finally was able to get the furnace to fail in my presence (it is intermittent). The light stayed solid the entire time. It tried to start 3 times, each time the ignitor came on, gas came on, and then it shut down. The light continually blinked once after it locked out, but again, solid the entire time until that point.

So I am still at a loss given I cleaned the flame sensor and just in case replaced it. Any other advice? Thanks in advance!

 

A solid LED is normal. One flash is lockout.

You'll need to test like a technician would.
Put a meter is series with the flame sensor to read operating ua. (microamps)
Connect an manometer to the pressure switch line to watch operating vacuum.
A voltmeter across the pressure switch to detect the switch opening.

I would clean the burner orifices as well as the burner carry over ports.
It's imperative that the flame sensor remain in the flame.
I would also check the manifold pressure since it's propane.

Downloadable manual - pdf
Diagnostics start on page 34.