FieldBench
Lennox codes

Lennox

Heat

Lockout

Heat fail

Heat section did not prove.

Walk Heat in Diagnose

Sign in for the next measurement

First check

1 Write the live code and watch one cycle

On Lennox LGT read Lennox current rooftop unit controller (not Landmark Prodigy) before you pull power. Write Heat exactly. Watch one full sequence and note which step dies. Ignition path in the heat section. Unit display names the fail.

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

  • Ignition path in the heat section. Unit display names the fail.

Plates that use Heat