Lennox
Fan
LockoutBlower fail
Indoor fan did not prove.
Walk Fan 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 Fan exactly. Watch one full sequence and note which step dies. Direct-drive ECM vs belt — this generation is often ECM.
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
- Direct-drive ECM vs belt — this generation is often ECM.