FieldBench
Lennox codes

Lennox

oC

Lockout

oC / OC — overcurrent

Keypad example: oC (Yaskawa) or OC. Output current trip. Locked rotor, dirty filters, or FLA set too low.

Walk oC in Diagnose

2 plates — walk the one on the cabinet

First check

1 Read the drive before you cycle power

On Lennox LGH photograph the VFD keypad or the unit-board fan alarm (OC, LU, OU, GF, OH, limp). Power-cycle wipes what you needed. Spin the wheel by hand (power off). Debris, seized bearing, belt wrapped.

Expect: Live drive code written down. Line voltage at L1/L2/L3 of the drive.

The rest of the walkthrough is Diagnose.

On the plates

  • Spin the wheel by hand (power off). Debris, seized bearing, belt wrapped.
  • Total external static vs this blower table. A rooftop with 1.4" TES and a 0.8" motor is an oC waiting to happen.
  • FLA / motor-data parameters vs the motor nameplate. Do not raise FLA to hide a dirty coil.
  • Ramp-up too fast on a high-inertia wheel — lengthen accel before you change a drive.

Plates that use oC

Same number, other makers

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