FieldBench
Lennox codes

Lennox

oH

Protect

oH — heatsink overtemp

Keypad example: oH. Drive thermal trip.

Walk oH 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. Drive fan spinning. Heat sink packed with roof lint.

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

  • Drive fan spinning. Heat sink packed with roof lint.
  • Cabinet door left off in the sun is not always the drive — still clean the sink.

Plates that use oH

Same number, other makers

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