Induced draft blower on Goodman furnace

I have a Goodman GMS8 furnace that is only 5 years old. We just bought this house and the induced draft blower runs continuously even when the thermostat is turned off. The only way to turn the blower off is turn the entire power off to the furnace. The LED diagnostic light always remains steady indicating there is no problem, but the manual states it should NOT run continuously. Can anyone help me out? Thanks

 

I'm not familiar with your furnace but the ID fan should be controlled by board-level logic. I suspect that it will require replacement of the control board. To double check try removing the red and white thermostat wires at the furnace connection point.

 

What will removing the red and white wire do or not do? I unplugged the ID blower while the heat was on and the burners turned off. Manual says the ID should kick off 15 seconds after the burners fire

 

If the thermostat wires are shorted together (being cut by duct sheetmetal can happen) disconnecting the thermostat wires at the furnace would shut the inducer motor off.

You are being asked to perform a SIMPLE TEST which will help to diagnose the problem.

Why people ask for help and then refuse to cooperate when they get it continues to be a mystery.

 

Probably nothing. The red is the power to the thermostat and the white is power back to the control board to initiate a call for heat. If the burners light, the room air blower comes on properly to raise the room temperature and when the thermostat is satisfied the burner goes off with the room air blower stopping shortly thereafter there is probably no problem with either the thermostat or connecting cable.

You MAY have a relay on the control board that takes the logic signal and converts it to power the ID fan. If this is true AND the relay is stuck in the closed position, it could be the problem. Unfortunately parts replacement on the control board just doesn't happen, mostly for insurance and regulatory reasons. You might try looking at the control board (main power to furnace off) and see if you can spot the relays. There will definitely be at least one for the room air blower (maybe two) and possibly others for different purposes. If you find them you can try rapping on the case smartly, but not heavily, to see if it will release.

Then again, your board may use solid-state relays which have no mechanical parts.

Wish I had more to offer.

 

Refuse? When did I refuse anything?

 

I removed the red and white wire and the blower still runs continuously. Blower turns on the second I power up the main power to the furnace

 

Did you remove the red and white wire from the stat?, or in the furnace. This is most important. If from the stat, that will not isolate a short in the stat wires. If you disconnected from furnace, then the problem is IN the furnace.

 

By "the blower," are you referring to the small inducer motor in the burner compartment, or the large fan that circulates air around the house?

 

Removed the wires in the furnace

 

Small motor In the burner compartment

 

According to the wiring diagram, there should be an equipment ground but I do not see a ground wire. It shows the same for the circular blower and I do see the ground wire for that. Could this be my problem? Or would it not even work if the ground was missing?

 

If you disconnected the red and white low volt wires on the furnace, and you still get 120 line voltage to the inducer, then the 24 vac x 120 vac relay(it is not called that, I just put it that way so you understand the function) is stuck. If that relay is on the board, you will need a new board, most likely, unfortunately. Have you tried rapping on any of those black box things on the board, with the butt end of a screwdriver, to see if that makes it shut off?

 

A missing ground wire would not cause the problem.

I agree with Ecman that this sounds like a circuit board that needs to be replaced.

 

The transformer? That is separate from the main control board

 

No. The red and white wire that hook up to about a 5 - 7 wire terminal strip that has all these different colored thermostat-size wires hooked to it. And the other issue was the relay. Nothing to do with the transformer, either.

The power in the furnace goes through your blower door switch (for safety) first. Then at a call for heat, 24 volt power leaves the R (red wire) terminal on that terminal strip in the furnace (which may or may not be on the control board), goes into the thermostat, comes back down the white wire for the heat circuit, goes into the W (white)terminal on the terminal strip. Then from there, usually about the first thing it does is go to a relay that lets the 24 volts from that thermostat circuit to activate a 120 volt circuit, to make the inducer motor(that runs on 120 volts) start up.

Sometimes when the relay goes out, the inducer will not even start. But conversely, if the relay gets arced, it might come on okay, but then stay stuck on because sometimes arced contacts do not leave go (close) when they are deenergized. What is supposed to deenergize is the 24 volts into that relay, after the call for heat is over.

 

I ordered and replaced the circuit board and now everything works correctly. Thanks for the help guys