Goodman, Amana GMSS9 / GCSS9 error code 3 flashes
Pressure switch circuit not closed
Goodman is the platform name, and your unit may not say it
Amana AMSS9 / ACSS9 is the same board with a different badge, so this page covers all of them. The fault, the checks and the parts are identical, which is why there is one page rather than one per brand.
Which models this applies to. Applies to every legacy flash furnace in this group: GMV8 / GMV9, GCH / GDH / GME / GMH, GDS / GHS / GMS / GKS, and GMN / GMP / GMT.
Quick answer
On Goodman GMSS9 / GCSS9 (2000s), 3 flashes is a fault. It means pressure switch circuit not closed. A first thing to check: Pressure tube cracked, disconnected or blocked.
- Applies to
- Goodman GMSS9 / GCSS9
- Goodman and Amana GMSS9, GCSS9, AMSS9, ACSS9 flash codes · Furnace · 2000s
- Type of code
- Fault
- Urgency: Stop using it
- First safe check
- Call for heat and listen. If the inducer is silent, the problem is the motor or its circuit, not the pressure switch.
What 3 flashes means on this model
The draft inducer spun up to pull air through the heat exchanger and the control never got confirmation that air was actually moving. Without that proof it will not release the gas. This is a safety interlock, not a nuisance alarm.
Symptoms you will notice
- Furnace will not fire
- You hear the draft blower for a few seconds and then it stops
- No heat
- Repeated lockouts with no ignition attempt at all
Common causes
The code tells you what the control detected, not which part failed. These are the causes we see most often, roughly in order of likelihood:
- Pressure tube cracked, disconnected or blocked
- Pressure switch failed, in either direction
- Draft inducer motor seized or spinning too slowly
- Blocked flue pipe, blocked vent, or a closed combustion air damper
- Condensate drain blocked on a high efficiency unit, flooding the switch area
- Weak or failed inducer capacitor on older single stage furnaces
What you can safely check
These are homeowner-level checks. None of them need you to open a live electrical compartment or work on gas.
- Call for heat and listen. If the inducer is silent, the problem is the motor or its circuit, not the pressure switch.
- Inspect the clear pressure tube for cracks and for water inside it.
- Go outside and look at the vent pipe. Look for debris, a bird nest, or a damper that has been left closed.
- On a 90 percent efficient or higher furnace, confirm the PVC drain line is open and draining freely.
Do not do these
- ×Do not bypass the pressure switch. This code exists because the control cannot prove the flue is clear, and forcing it can send combustion gases into your home.
- ×Do not run the unit with the burner door open.
- ×Do not ignore a code that keeps coming back.
When to call a technician
Stop using the appliance and call today
This one is a safety limit, not a nuisance. The control is shutting the unit down to prevent damage or a hazard, and it will keep doing that until the underlying cause is fixed. Running it anyway risks the expensive failure it was designed to prevent.
- This is a fuel-burning appliance, so treat anything involving a burner, gas valve or flue as technician work. If you smell gas at any point, leave the property and call the gas utility from outside rather than continuing to diagnose.
- If the appliance has stopped mid-cycle, is making a noise you have not heard before, or smells burnt, stop reading here and call. Those are symptoms of something the fault code does not describe well enough.
Clearing a vent blockage and clearing a condensate drain are homeowner work. Anything involving the inducer motor or gas train is not.
What it costs to fix
Parts
Inducer motor $150 to $400. Pressure switch $30 to $90. Capacitor $15 to $40. Inducer wheel $20 to $60.
Labor
One to two hours. Add time if the flue has to be roped up to find a blockage.
DIY or technician
Clearing a vent blockage and clearing a condensate drain are homeowner work. Anything involving the inducer motor or gas train is not.
Typical US part and labor ranges, 2026. They vary by region, model and contractor, so treat them as a planning figure, not a quote.
Scope of this code
- Code table
- Goodman and Amana GMSS9, GCSS9, AMSS9, ACSS9 flash codes
- Models in scope
- Goodman GMSS9 / GCSS9, 2000s
- Checked
- Confirm on your own unit
- Find the model number on the data plate, then check this code in the service manual for that model. Manufacturers revise code tables between model years, and a revised board can renumber a fault.