Trane Mini Split 4-TIME BLINK Error Code

Updated 2026-08-30 · review status: manual-verified · reviewed by MiniSplitDecoder Editorial Team Last verified: 2026-08-30

Check your model first

  • Trane ML series (Mitsubishi-built NTXWMT/NAXWMT) service manual

Match the model on your equipment label to the linked manufacturer documentation. The same code can mean different things across model families.

Quick answer

4-TIME BLINK on Trane mini splits means indoor control system trouble - the indoor controller cannot read data in its nonvolatile memory, and Trane's failure-mode table directs indoor PCB replacement. Power cycle once; a recurring 4-time blink means the indoor board needs a technician.

Severity: high · DIY difficulty: easy

Safety

Stop at the breaker power-cycle and any plug-accessible checks (filters, remote settings, visible wiring). The outdoor unit's capacitor holds a lethal charge and the refrigerant circuit is both pressurized and (on R-32 units) flammable — opening panels or servicing the sealed system is licensed-technician work (EPA 608).

What 4-TIME BLINK means

Trane's troubleshooting table lists 4-TIME BLINK as indoor control system trouble. The service manual says the indoor controller cannot read data in nonvolatile memory and directs replacement of the indoor electronic control P.C. board in the failure-mode table.

Code meaning varies by series

  • Trane ML series (Mitsubishi-built NTXWMT/NAXWMT) service manual: Indoor electronic control P.C. board nonvolatile memory read failure - remedy per manual is PCB replacement

First checks before service

This page currently documents the safe reset triage. If the code returns, use the linked source manual or a qualified technician for code-specific diagnosis.

  1. 1. One-time fault event (power disturbance or transient sensor reading) common DIY

    Check: Power-cycle at the breaker/disconnect (or unplug for CPAP), restore, and run the system while watching for the code.

    Fix: If the code does not return after a full run cycle, the fault was transient — monitor, no repair needed.

  2. 2. Fault persists after a clean reset occasional pro only

    Check: If the code returns immediately or every session, note the conditions (startup, heating, after rain).

    Fix: A persisting code points at the component the manual assigns to this code — that repair is technician territory.

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Sources

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