AMANA DIAGNOSTIC REFERENCE DUAL 7-SEGMENT DISPLAY (TWO-STAGE VARIABLE-SPEED) DOC AMANA-B3

Amana furnace: ECM Motor in a Limiting Condition (b3)

Q: What does b3 mean on a Goodman furnace?

ECM Motor in a Limiting Condition (b3). The ECM hit a power, speed, or temperature limit and reduced output — the furnace keeps running at reduced airflow. Officially caused by blocked/clogged filters, restrictive or undersized ductwork, blocked inlet, or high ambient heat.

b3 YOUR LIGHT: DISPLAY CODE B3 — MATCH IT ABOVE

Try DIY first, then call a pro

What does b3 mean on a Goodman furnace? The ECM hit a power, speed, or temperature limit and reduced output — the furnace keeps running at reduced airflow. Officially caused by blocked/clogged filters, restrictive or undersized ductwork, blocked inlet, or high ambient heat.

GOOD NEWS: THE FIRST CHECKS ARE FREE AND TAKE MINUTES.

Try these first — in this order

Fresh filter, open all vents, clear the blower inlet.

1Check: Clogged filter / restrictive ducts (power limit)

2Check: Blocked inlet (speed limit) or high ambient temperature (temp limit)

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Duct sizing evaluation if it persists. DIY part cost: $5–25 — a pro visit for this class of fault typically runs $150–350.

What causes it (in order of likelihood)

Clogged filter / restrictive ducts (power limit) DIY-CHECKABLE
Blocked inlet (speed limit) or high ambient temperature (temp limit) DIY-CHECKABLE

Parts referenced by this code

Air Filter (check size on the old one)

$5–25

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Always match parts against your model's parts list — part numbers vary within a series.

Applies to

GMVC96 · GCVC96 · AMVC96 · ACVC96

Different Amana generations use different code maps. If your series isn't listed, don't assume this meaning — check your blower-door label.

Verified against Goodman GMVC96/GCVC96 Service Manual, p.45

Last verified 2026-07-06 · how we verify