Goodman, Amana APG13 error code 8 flashes
Indoor or outdoor thermostat open, cooling only
Goodman is the platform name, and your unit may not say it
Amana APG13 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.
Quick answer
On Goodman APG13 (2000s), 8 flashes is a fault. It means indoor or outdoor thermostat open, cooling only. A first thing to check: Loose wire at the furnace or air handler terminal block.
- Applies to
- Goodman APG13
- Goodman and Amana APG13, GPG13, APG15 combined furnace and AC flash codes · Furnace · 2000s
- Type of code
- Fault
- Urgency: Worth keeping an eye on
- First safe check
- Check that every wire is firmly seated at the terminal block where the thermostat wires land.
What 8 flashes means on this model
The indoor thermostat wiring, or a switch on the indoor unit, is reading open. On a heat pump that runs cooling only, this code appears when the control is expecting a closed circuit from the thermostat and is not getting one. It is often a loose wire at the terminal block.
Symptoms you will notice
- Thermostat calls for cooling, nothing happens
- Indoor blower may or may not run
- Outdoor unit never starts
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:
- Loose wire at the furnace or air handler terminal block
- Failed thermostat or thermostat wiring
- Failed indoor control board
- Failed safety switch such as a high limit or float switch
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.
- Check that every wire is firmly seated at the terminal block where the thermostat wires land.
- Check whether the indoor blower runs when cooling is called. That tells you whether the control is getting the call at all.
Do not do these
- ×Do not bridge safety switches to make cooling start.
When to call a technician
No call needed yet, but write it down
Note the date and the exact code, and watch whether it comes back. If it turns into a repeat fault or starts affecting performance, that is when it becomes worth a technician.
- 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.
Re-seating a loose terminal is fine. Board and thermostat work is straightforward but easy to do wrong.
What it costs to fix
Parts
Wiring and terminals are usually free. Thermostat $50 to $250. Indoor board $150 to $350.
Labor
Under an hour in most cases.
DIY or technician
Re-seating a loose terminal is fine. Board and thermostat work is straightforward but easy to do wrong.
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 APG13, GPG13, APG15 combined furnace and AC flash codes
- Models in scope
- Goodman APG13, 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.