9 blinks, 2.5 s OFFMitsubishi Electric · MSZ / MSY / MUZ / MUY GL NA series · Mini Split

Mitsubishi Electric MSZ / MSY / MUZ / MUY GL NA series error code 9 blinks, 2.5 s OFF

Control board memory, or a shorted power module

Needs attention soon

Also written as nine blinks, 09, non-volatile memory, IGBT, power module

Quick answer

On Mitsubishi Electric MSZ / MSY / MUZ / MUY GL NA series, 9 blinks, 2.5 s OFF is a fault. It means control board memory, or a shorted power module. A first thing to check: A failed inverter P.C. board that can no longer read its own memory.

Applies to: Mitsubishi Electric MSZ / MSY / MUZ / MUY GL NA series; Mitsubishi Electric MR SLIM GL series split codes · Mini Split
Type of code: Fault; Urgency: Needs attention soon
First safe check: Read the inverter LED first: five blinks is memory, six is a short. Replacing the board when the real fault is a shorted compressor winding is an expensive mistake.

Checked 2026-09-26

What 9 blinks, 2.5 s OFF means on this model

Split by the inverter LED into two very different faults. A five time LED blink means the non-volatile memory data cannot be read properly and the manual gives one remedy, replace the inverter P.C. board. A six time LED blink means the interface has short circuited in the output of the power or IGBT module, or the compressor winding itself has short circuited.

Symptoms you will notice

Upper lamp blinks nine times after a three second hold, no beep
The system will not start at all
The system worked before and stopped suddenly
A five time LED blink points at the board, a six time blink points at a short

Common causes

The code tells you what the control detected, not which part failed. These are the causes we see most often, roughly in order of likelihood:

A failed inverter P.C. board that can no longer read its own memory
A power supply failure on the inverter board, often after a power event
A short circuited output on the power or IGBT module
A compressor winding that has short circuited
A connector or board fault that has damaged the module

What you can safely check

These are homeowner-level checks. None of them need you to open a live electrical compartment or work on gas.

Read the inverter LED first: five blinks is memory, six is a short. Replacing the board when the real fault is a shorted compressor winding is an expensive mistake.
Check the compressor connector and the wiring to the module, since a short is often in the connection rather than the part.
If the unit worked before a power event, suspect the board power supply section.

Do not do these

×Do not replace the inverter P.C. board on a six time LED blink without finding the short. A shorted compressor winding will destroy the new board too.
×Do not keep restarting, because a shorted module or winding does not clear itself.
×Do not work inside the outdoor unit with the power switch on.

When to call a technician

Book a technician, do not keep resetting it

This fault will not clear on its own. Every power cycle gives the control one more failed attempt, and repeated attempts are what turn a cheap part replacement into a seized or contaminated system.

The refrigerant circuit is sealed and legally requires licensed handling. Opening it without certification releases refrigerant and can put the whole system in violation of regulation, so a low-pressure or high-pressure fault on this equipment is a call-out, not a weekend job.
If the appliance has stopped mid-cycle, is making a noise you have not heard before, or smells burnt, stop reading here and call. Those are symptoms of something the fault code does not describe well enough.

A licensed technician job. Tracing a short is not a homeowner task.

What it costs to fix

Parts

Inverter P.C. board $500 to $1,200. Power or IGBT module $200 to $600. Compressor $1,400 to $3,000.

Labor

Three to eight hours, and much longer if a short has to be traced.

DIY or technician