Amana AMSS920803BN Error Code 3 Flashes: Pressure Switch Stuck Open

What Does Code 3 Flashes Mean?

Three flashes on the Amana AMSS920803BN indicate a pressure switch that is stuck open. The induced-draft blower runs continuously, but the pressure switch never closes to confirm adequate draft, so the Integrated Control Module will not allow gas to reach the burners. This protects against firing without proven venting.

Because the AMSS920803BN is a 92% AFUE condensing furnace, it has a secondary heat exchanger and a condensate drain — parts that older non-condensing furnaces lack. That matters here: a clogged condensate drain or trap can back up and hold the pressure switch open, a cause that simply does not exist on a standard-efficiency unit. The most common trigger, though, is a blocked, pinched, or disconnected pressure-switch hose, followed by a blocked exhaust flue or intake pipe (often shared PVC runs), a clogged drain, or a weakening inducer motor.

This code is the mirror image of two flashes (code-2), where the switch is stuck closed before the inducer starts. Here the inducer is running as it should, but the switch fails to respond, so the two codes describe opposite failures of the same pressure-switch system.

What You'll Notice

• You hear the inducer motor running continuously but the burners never light
• The single diagnostic LED blinks three times, pauses, and repeats
• The furnace runs the draft blower, then shuts down without producing heat
• In cold weather, a frozen or snow-blocked outdoor vent termination may be visible
• Standing water near the furnace base can point to a clogged condensate drain

Common Causes

How This Is Diagnosed

A technician works from the most common cause outward. They first inspect the pressure-switch hose for kinks, condensate, or a loose fit, then check the exhaust flue and intake pipe for blockage, sagging, improper length, or a covered termination. Next they check the condensate drain and trap for a backup, then verify inducer performance and finally the switch setpoint and contacts. Because this is a condensing furnace, the drain and venting checks carry extra weight compared with older equipment.

When to Call a Professional

This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:

• The inducer runs but the furnace never ignites (three flashes)
• The exhaust or intake pipe is blocked, sagging, or holding standing water
• The condensate drain is clogged or leaking
• The code appears mainly in very cold weather, suggesting a frozen vent termination
• The inducer motor sounds weak, loud, or fails to start

✓ Verified against manufacturer service manual — March 2026