Goodman GDT090-4B

[Jeffrey Bennett]

Looking for advice. My Goodman GDT090-4B furnace is not operating consistently. Sometimes it will not light and display a single flash error code. Sometimes it will light and run for a minute or two then the flame turns off and it will display a single flash error code. According to the manual the single flash error code indicates one of the following: problem with gas flow, problem with gas pressure, problem with gas pressure or problem with the flame sensor (no flame detected).

Since encountering this issue I have: replaced the flame sensor, replaced the gas valve, had the gas company check the gas pressure and flow.

I have also checked the operation electrically by validating the unit is sending 24v to the gas valve when it wants it open.

Any ideas as to what the issue may be would be appreciated.

It is a propane system and I do have another furnace on the system and it works fine.

Thanks!

 

[Stuff]

Do the flames look good when it is running? All burners look the same?

Could be bad ground. Otherwise control board.

 

[Sponsor]

 

[Jeffrey Bennett]

All the flames look the same and look good.

If it is a bad ground is there a way to check for that?

How could I determine if it is the control board?

The issue is intermittent which makes it difficult to troubleshoot.

Thanks for the reply.

 

[Dana]

Flame sensors can develop a glaze or carbonization that prevents the sensor from delivering the right signal level, producing intermittent performance before eventually causing it to not work at all. Sometimes they can be cleaned up with a plastic scouring pad, sometimes not. Using sandpaper can damage it.

 

[Stuff]

You can use a multi-meter and measure resistance between ground and neutral at the furnace. Then the burner and ground. Goodman's docs say to verify less than 10 ohms. Real life should be less than 1 ohm. The green ground wire comes from the power line and should be secured to the cabinet. Then check the ground and neutral wires coming into the furnace, at the disconnect switch, and at the electrical panel.

Control board is hard to check. It feels like just throwing parts at the problem but easier to just replace. Go with ICM280 as available cheaper replacement.

Also - try disconnecting everything and putting back together as may be bad connection.