FieldBench
Trane codes

Trane

Contactor

Lockout

Contactor / coil

Will not pull, chatters, or is welded.

Walk Contactor in Diagnose

4 plates — walk the one on the cabinet

First check

1 Is Y actually at the contactor?

On Trane XR16 a silent outdoor is often no Y. Measure 24 VAC coil-to-C at the contactor on a cool call. 24 VAC at the coil under a Y call. Low voltage = long stat wire, weak indoor transformer, or a furnace 24 (fuse) problem.

Expect: ~24 VAC at the coil when the indoor is calling.

If fail: Indoor Y / IFC / stat — not a capacitor.

The rest of the walkthrough is Diagnose.

On the plates

  • 24 VAC at the coil under a Y call. Low voltage = long stat wire, weak indoor transformer, or a furnace 24 (fuse) problem.
  • Coil ohms / burned turns. Pitted or welded points — replace, do not file and leave.
  • Chatter: low 24V, bad coil, weak transformer — not an inverter ramp.
  • 24 VAC across the coil. Then dual cap (if this chassis has one) or VFD / two-stage unload.
  • 3-phase: phase loss, reverse rotation. A scroll run backwards is loud and pumps no gas.
  • Internal overload. Let it cool; find why it overheated.

Plates that use Contactor

Same number, other makers

Contactor on Trane is not the same code on these plates.