FieldBench
Lennox codes

Lennox

Comm

Lockout

ABCD / outdoor drop

Drive or bus. Wall control loses the outdoor.

Walk Comm in Diagnose

2 plates — walk the one on the cabinet

First check

1 Let it cool, then read the drive LED

On Lennox EL18XCV overcurrent / overheat is often a dirty coil, a failed OD fan, or a locked compressor — not a dead inverter. Clear airflow, confirm the OD fan, and read the drive LED before you order a control. ABCD landing and polarity, outdoor board power, inverter comms harness.

Expect: OD fan running. Coil clean. Drive LED decoded from THIS outdoor’s card.

The rest of the walkthrough is Diagnose.

On the plates

  • ABCD landing and polarity, outdoor board power, inverter comms harness.
  • C still required at the wall control.
  • Indoor must be Infinity-capable. A 24ACC6-style indoor pairing is the wrong mental model.

Plates that use Comm

Same number, other makers

Comm on Lennox is not the same code on these plates.