American Standard AUH1B080A9H31A Error Code Continuous OFF: Check Power

What Does Code Continuous OFF Mean?

When the diagnostic LED on your American Standard AUH1B080A9H31A is completely dark, the White-Rodgers 50A65 Integrated Furnace Control (IFC) is receiving no power at all. Without power the board cannot run the furnace in any mode or even display another flash code, so a dark LED is the board's way of telling you to check its power supply first.

This is one of the more approachable conditions because the cause is almost always outside the furnace. The most common reason is a tripped circuit breaker at the electrical panel, followed by the furnace's own power switch being turned off — it often looks like an ordinary wall light switch near the unit and is easy to flip by accident. A blown low-amp fuse on the IFC board (tripped by a wiring short or power surge) is a third possibility.

It is worth noting how this differs from a solid, non-blinking LED: a dark LED means no power is reaching a healthy board, while a steady light means the board has power but has failed internally and needs replacement. A dark LED is the condition most likely to be fixable by a homeowner, and because there is no power, there is no active hazard from the furnace itself while you check the breaker and switch.

What You'll Notice

• The diagnostic LED is completely dark with no flashing when viewed through the window.
• The furnace does not respond at all to a thermostat heat call — no inducer, igniter, or blower.
• Other electronics on the same circuit may also be dead if a breaker has tripped.
• A wall switch near the furnace or a toggle on the cabinet is found in the OFF position.

Common Causes

How to Fix It: Restore Power to the Furnace

What You'll Need

• Flashlight

Steps

1. Turn off the furnace power switch and shut off the gas supply before inspecting For safety before you work, set the furnace power switch (and the HVAC breaker) to OFF, and turn the gas supply valve to the OFF position (handle perpendicular to the pipe). If you smell gas at any point, leave your home immediately and call your gas company from outside.
2. Check the circuit breaker at the electrical panel Find the breaker labeled for 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 flipping it fully to ON. If the breaker trips again immediately, stop and call a professional — a repeated trip signals an electrical fault that is not safe to reset repeatedly.
3. Confirm the furnace power switch is on Look for a standard-looking light switch on the wall near the furnace or on the furnace cabinet itself. It is often mistaken for a room light switch and left off. Set it to ON.
4. Inspect the control board fuse (if visible) With the panel off and power still down, look on the IFC for a small automotive-style blade fuse (commonly 3 or 5 amp). If it is visibly blown, that points to a wiring short or surge; you can replace it with an identical-rating fuse, but if it blows again, a technician should find the short rather than you continuing to replace fuses.
5. Restore gas supply, then power Reinstall the access panel, turn the gas supply valve back to ON (handle parallel to the pipe), then set the furnace power switch and breaker back to ON. Wait a moment for the board to initialize.
6. Verify the LED status Look through the viewing window. After power is restored you should see a slow flash, which is normal standby.

When to Call a Professional

Contact a licensed HVAC technician if:

• The circuit breaker trips again immediately after you reset it
• The furnace power switch and breaker are both ON but the LED stays dark
• The control board fuse blows again after being replaced with the correct rating
• There is a burning smell or visible signs of scorching or melted wiring near the furnace

✓ Verified against manufacturer service manual — March 2026