FieldBench
Lennox codes

Lennox

Cool alarm

Lockout

Prodigy cool

Mechanical cool did not prove.

Walk Cool alarm in Diagnose

Sign in for the next measurement

First check

1 Write the live code and watch one cycle

On Lennox LGH read Prodigy unit controller (Landmark) before you pull power. Write Cool alarm exactly. Watch one full sequence and note which step dies. Economizer status on Prodigy first.

Expect: Call: Occupied / G starts the indoor fan. Y1 is cool. W is gas heat. They are different boards in the same box.

The rest of the walkthrough is Diagnose.

On the plates

  • Economizer status on Prodigy first.
  • Y1 output, contactor, HPS/LPS, 3-phase.

Plates that use Cool alarm