Amana
b3 / b9
ProtectMotor limiting / low indoor airflow
b3 = folding back on power/speed/temp (reduced CFM). b9 = airflow below calculated minimum.
Walk b3 / b9 in Diagnose
2 plates — walk the one on the cabinet
First check
1 Airflow before you touch the limit
On Amana ARVT96 a limit is airflow or overfire until proven otherwise. Do not replace the limit first. Filter, blower wheel, A-coil, and the heat-speed setting for THIS motor (tap, model plug, or communicating CFM — not a sister SKU chart). Filter, coil, TES. Heat ESP must stay ≤ 0.5" on this SS — a brick duct is b9 / E3, not a bad motor.
Expect: Heat CFM: SS rec. high-heat: 0403BN 1025 · 0603BN 1200 · 0803BN 1400 · 0804CN 1760 · 1005CN 1770 · 1005DN 2000 · 1205DN 2150.
The rest of the walkthrough is Diagnose.
On the plates
- Filter, coil, TES. Heat ESP must stay ≤ 0.5" on this SS — a brick duct is b9 / E3, not a bad motor.
- IFC heat CFM vs the SS rec. CFM for this SKU (1025–2150).
- Return undersized or a 5" media cabinet the installer added.
- Filter, coil, closed registers, undersized return, TES.
- CoolCloud tonnage / CFM vs the outdoor and the coil.
- A communicating motor will ramp into a brick and then b9.