Goodman GM9S960803BNAB Furnace, burner intermittently goes out.

drakerobs

I have a new Goodman GM9S960803BNAB furnace. On a call for heat normal sequence of operation occurs. Inducer motor turns on, my inducer pressure switch closes. (rated for -1.27 PF Manometer reads 1.5-1.6). All safety circuits are working properly and nothing is jumped out. Burner lights and fan is set to 25 second delay before turning on. Sometimes as soon as i hear the relay in the board click for fan the burner shuts off completely. Other times the fan turns on with the burner lit and the flames stays on for 20-30 minutes without any problems. All wiring has been checked including grounds and factory Molex plugs. All of the safety's are working properly because the furnace relights every time until it locks out on ignition trials. I've tried it with jumpers straight from the board itself ruling out the thermostat and the stat wiring. I've also checked the air filter and both the flue and intake pipes for plugs or blockages and the drains and factory installed condensate trap. The only thing I am left with is an internal short happening intermittently in the board. i am just at a loss because the furnace is only a year old. Any help or advice would be appreciated. Thanks.

EBEBRATT-Ed

If you have a thermostat where you can switch the fan to the "ON" position try that and see if it changes anything.

But I am thinking the fan starting has nothing to do with your issue. Could be a defective flame sensor. Also check the wiring to the flame sensor and unplug and plug any connections to make sure they are tight.

drakerobs

Yes tried the fan "on" setting, the issue still happens. Plugs seemed normal to me and were not loose. Could the flame sensor work intermittently like that? And it is just a coincidence that it happens to shut off when the fan turns on?

drakerobs

I've amped out the inducer motor and everything seems normal and I'm not loosing draft either.

EBEBRATT-Ed

It does seem strange that it cuts off when the fan starts. I would check the wiring as the voltage could dip under a heavy load if you have a bad connection.

Did it fail when you had the fan on all the time?

Is it a hot surface ignitor with a separate sensor? What do you have.

drakerobs

Hot surface igniter with a separate flame sensor on the opposite side of the burners. And yes the problem still happened with the fan on all the time. After the first time the burner lights and goes out when the fan turns on it relights with no issues. Although the flame almost fluttered but stay lit.

EdTheHeaterMan

Depending on the environment, the flame sensor circuit can be the problem. In some areas where the furnace is located in a damp basement, or in an outdoor accessible closet at coastal communities, the corrosive nature of the air used for combustion can cause a build up on the flame sensor rod.   The flame sensor circuit uses “Micro Amps” of DC  electrical current to prove the flame.  A low voltage Alternating Current signal is sent to the flame sensor probe.  The flame acts as a rectifier to change the signal to a very sensitive DC signal that returns to the control by way of the burner and chassis ground.  If that signal is interrupted by corrosion, then you will have intermittent flame signal problems.  

Is the furnace located in a laundry room? Sometimes cleaning chemicals stored near the furnace can have the same effect.  That is the first place I would look.  See if the flame sensor has a white powdery coating.  If it does, then use a very fine sandpaper or scotchbrite pad to clean off the probe portion that is exposed to the flame.  

If it is a bad control board, there is a 5 years warranty on that board, and if you register it online before you order the part, you may get a 10 year warranty on all the parts.   

Just say that you purchased the furnace within the last 90 days in order to get the longer warranty.  (like a new home that has been sitting on the market for a couple of months before you owned it would have an older furnace burt you are the new owner of the furnace)

drakerobs

Yes the furnace is located next to washer and drier in a medium sized room in the basement. i do have the extended warranty so parts aren't an issue.

drakerobs

does anyone know if there is a specific measurement range for the goodmans or is it roughly 3-5 microamps.