FieldBench
Trane codes

Trane

E4.1

Protect

Open reverse-airflow limit

Trane S9V2 alarm table: reverse-airflow limit is open.

Walk E4.1 in Diagnose

2 plates — walk the one on the cabinet

First check

1 Airflow before you touch the limit

On Trane S8V2 a limit is airflow or overfire until proven otherwise. Do not replace the limit first. Filter, blower wheel, A-coil, and the heat-speed setting for THIS motor (tap, model plug, or communicating CFM — not a sister SKU chart). Multi-poise cabinet — find the reverse-airflow switch for THIS orientation (blower-inlet / opposite the heat exchanger).

Expect: Rise in the rating-plate window. Static vs this cabinet’s blower chart.

The rest of the walkthrough is Diagnose.

On the plates

  • Multi-poise cabinet — find the reverse-airflow switch for THIS orientation (blower-inlet / opposite the heat exchanger).
  • VS heat CFM in the IFC menu (no dips). Filter, coil, return. Rise vs plate.
  • A missing or unplugged reverse-airflow jumper/switch on a converted orientation throws E4.1 with a cold exchanger.
  • Other limit / rollout decimals — confirm on THIS S9V2 door card / service facts. Do not invent E4.2 / E4.3 titles.

Plates that use E4.1