FieldBench
Carrier codes

Carrier

Limit

Protect

Limit / aux limit

Heat-exchanger or supply limit opened.

Walk Limit in Diagnose

2 plates — walk the one on the cabinet

First check

1 Airflow before you touch the limit

On Carrier 48FC 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). Filters, belt, blower rotation (3-phase indoor motors reverse).

Expect: TES / static: External static vs the blower table for this tonnage — rooftops run dirty.

The rest of the walkthrough is Diagnose.

On the plates

  • Filters, belt, blower rotation (3-phase indoor motors reverse).
  • Rise vs the rating plate. Overfire and low CFM look the same from the roof.
  • Heat-section panel gasket / blocked return in the curb.

Plates that use Limit

Same number, other makers

Limit on Carrier is not the same code on these plates.