FieldBench
Carrier codes

Carrier

A2L

Hazard

A2L / mitigation

Leak sensor or mitigation input on an R-454B cabinet.

Walk A2L in Diagnose

Sign in for the next measurement

First check

1 Confirm this pair is actually A2L

On Carrier 48FE FE3 / LE4 / SE5 / rE6-class codes are only valid when this furnace is tied to an R-32 or R-454B outdoor. On R-410A this is a miswired mitigation harness — not a leaking indoor coil.

Expect: Outdoor refrigerant from the outdoor nameplate, not from memory.

If fail: Remove / correct the mitigation harness. Do not condemn the IFC.

The rest of the walkthrough is Diagnose.

On the plates

  • Only legal on the A2L plate. A leftover 410A 48FC will not have this harness.
  • Find the leak. Do not disable the sensor to ‘get cooling back.’

Plates that use A2L