American Standard AUD1B080A9H31A Error Code Continuous OFF: Check Power
What Does Code Continuous OFF Mean?
When the diagnostic LED on the American Standard AUD1B080A9H31A is completely dark, the White-Rodgers 50A65 Integrated Furnace Control (IFC) is receiving no power at all. With no power, the board cannot run any mode and cannot even display a fault code — so an unlit LED is itself the diagnosis: get power back to the board.
This is the opposite condition of a Continuous ON, where the board has power but has failed its own self-test (Replace IFC). Here the board is likely fine; the interruption is almost always upstream of it. The most common cause is a tripped circuit breaker, followed by the furnace's own power switch being turned off — on many installs this looks exactly like an ordinary light switch mounted on or beside the furnace cabinet, and it gets flipped off by accident. A blown low-voltage fuse on the board or a door-interlock switch that is not being depressed by the blower-compartment panel can also cut power.
Because the AUD1B080A9H31A has no power in this state, there is no active ignition or gas flow and no immediate hazard from the furnace itself. Restoring power at the breaker or switch resolves the majority of cases; if power is confirmed present and the LED stays dark, the fault is internal and needs a technician.
What You'll Notice
- The diagnostic LED behind the furnace sight glass is completely dark with no flash of any kind.
- The furnace does nothing on a heat call — no inducer, no igniter glow, no blower.
- A breaker in the electrical panel is in the middle 'tripped' position, or the switch on/near the furnace is off.
- The blower-compartment door was recently removed or is not fully seated against its interlock switch.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Tripped circuit breaker or blown fuse | Most common | ✓ DIY fix → |
| Furnace power switch turned off | Common | ✓ DIY fix → |
How This Is Diagnosed
The logic runs from the outside in: confirm the panel breaker is not tripped, then the furnace disconnect switch is on, then the access panel is fully closing the door-interlock switch. If line power is verified at the furnace but the board's LED is still dark, a technician measures voltage into the board and checks the on-board low-voltage fuse and the transformer before condemning any part.
How to Fix It: Restore Power to the Furnace
What You'll Need
Steps
- Turn off power at the furnace switch and shut off the gas supply as a safety precaution Before inspecting anything, set the furnace's own power switch to OFF and turn the gas supply valve (usually a handle on the gas pipe near the furnace) to OFF, perpendicular to the pipe. This ensures the furnace cannot attempt ignition the moment power is restored while your hands are near it. If you smell gas at any point, leave your home immediately and call your gas company from outside.
- Check the circuit breaker at the electrical panel Find the breaker serving the furnace or HVAC system. A tripped breaker sits in the middle position between ON and OFF. Reset it by pushing it firmly to OFF first, then back to ON. If it trips again immediately, stop — do not keep resetting it — and call a professional, as that indicates a short.
- Confirm the furnace power switch and door panel Locate the switch on the wall near the furnace or on the cabinet and make sure it is ON — it is easily mistaken for a light switch. Also confirm the blower-compartment access panel is fully seated, since a loose panel can hold the safety door-interlock switch open and cut power.
- Restore gas and power, then observe the LED Turn the gas valve back to ON (parallel to the pipe), set the furnace switch to ON, and look through the sight glass. Within a moment the diagnostic LED should light and begin a slow flash, indicating the board has power and is in normal standby.
When to Call a Professional
Contact a licensed HVAC technician if:
- The circuit breaker trips again immediately after you reset it.
- The breaker is on, the furnace switch is on, the panel is seated, yet the LED remains completely dark.
- You see or smell signs of electrical damage — scorching, melted insulation, or a burning odor — near the furnace.
- You smell gas at any point during the process.
Frequently Asked Questions
Why is there no light at all on my American Standard AUD1B080A9H31A control board?
A dark LED means the White-Rodgers 50A65 board has no power. Check the circuit breaker, the furnace power switch, and that the blower door is fully closed before assuming the board has failed.
Is a dark LED dangerous?
The furnace itself poses no active hazard with no power, since it cannot ignite. The caution is at the electrical panel: if the breaker trips again right after resetting, stop and call a professional.
I restored power but the light is still off — now what?
If the breaker and switch are confirmed on and the panel is seated but the LED stays dark, the problem is inside the furnace (a blown board fuse, bad transformer, or wiring fault) and needs a technician.
Sources
✓ Verified against manufacturer service manual — March 2026