Trane UPPER LAMP 4-TIME BLINK error code

What it means

Trane's troubleshooting table lists this pattern as indoor control system trouble. The service manual says the indoor controller cannot read data in nonvolatile memory and directs PCB replacement in the failure-mode table.

Urgency

Likely causes

1. The indoor controller cannot read stored memory data
2. The indoor electronic control PCB needs service or replacement
3. A power or control-board fault did not clear after reset

Homeowner fix

Power cycle the system once at the breaker if you can do that safely. Do not open the indoor cabinet or touch the control board.

When to call a pro

Call a licensed HVAC technician if the 4-time blink returns. Tell them Trane identifies this as indoor control system nonvolatile-memory trouble.

Repair vs replace

A single indoor board repair can be reasonable. Compare replacement if the system is older, out of warranty, or has repeated board failures.

• Trane ML Series 9,000 BTU R-410A 115V (NTXWMT09A111AA / NTXSMT09A111AA)

  ML Series R-410A

• Trane ML Series 12,000 BTU R-410A 115V (NTXWMT12A111AA / NTXSMT12A111AA)

  ML Series R-410A

For your technician

Technician note: verify supply power and connectors, then diagnose the indoor electronic control PCB per Trane's indoor control system troubleshooting. Page context: Trane maps this display to the ML Series R-410A line; source: Trane MyLinkDrive NTXWMT-A111A(B) Service Manual, Section 9 Troubleshooting; display convention: match the letter U, letter P, letter P, letter E, letter R, letter L, letter A, letter M, letter P, four, letter T, letter I, letter M, letter E, letter B, letter L, letter I, letter N, and letter K marker exactly before comparing neighboring codes.

Which systems show it

ML Series R-410A

Related troubleshooting

Use the symptom guide alongside the exact display code if the unit is flashing, cycling, or showing comfort symptoms.

Related codes

Source

Next step