Amana
b3
ProtectMotor limiting (power / speed / temp)
ECM is folding back on power, speed, or temperature. Furnace keeps running at reduced CFM.
Walk b3 in Diagnose
2 plates — walk the one on the cabinet
First check
1 Airflow before you touch the limit
On Amana AMVC96 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, and total external static vs the AMVC96 blower chart.
Expect: Rise in the rating-plate window. Static vs this cabinet’s blower chart.
The rest of the walkthrough is Diagnose.
On the plates
- Filter, coil, and total external static vs the AMVC96 blower chart.
- Return undersized or a 5" media cabinet the installer added.
- High ambient around the motor (closet, no ventilation).
- This is Category I metal vent. There is no 96% collector or PVC trap to prime.
- Cap, liner, common-vent tables, inducer wheel, hose on the inducer housing.
Plates that use b3
Same number, other makers
b3 on Amana is not the same code on these plates.