FieldBench
Lennox codes

Lennox

HPS / LPS

Lockout

Pressure protection

Still real on an inverter.

Walk HPS / LPS 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. Coil, fan, charge by weigh-in — you do not ‘top off’ a Greenspeed.

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

The rest of the walkthrough is Diagnose.

On the plates

  • Coil, fan, charge by weigh-in — you do not ‘top off’ a Greenspeed.
  • Outdoor fan that is actually the inverter-driven fan, not a dual-cap PSC motor.
  • Do not use 24ACC6 piston superheat as the pass/fail.

Plates that use HPS / LPS

Same number, other makers

HPS / LPS on Lennox is not the same code on these plates.