64Fujitsu · ASTG09 / ASTG12 / AOTG09 / AOTG12 KMTC · Mini Split

Fujitsu ASTG09 / ASTG12 / AOTG09 / AOTG12 KMTC error code 64

Active filter or power factor correction circuit error

Needs attention soon

Also written as pfc, power factor, active filter, code 64

Quick answer

On Fujitsu ASTG09 / ASTG12 / AOTG09 / AOTG12 KMTC, 64 is a fault. It means active filter or power factor correction circuit error. A first thing to check: A failed power factor correction circuit on the inverter board.

Applies to: Fujitsu ASTG09 / ASTG12 / AOTG09 / AOTG12 KMTC; Fujitsu GENERAL AIRSTAGE KMTC wall split codes, indoor and outdoor · Mini Split
Type of code: Fault; Urgency: Needs attention soon
First safe check: Check the supply voltage and its stability, because a persistent overvoltage or a brownout will keep damaging this circuit even after a replacement.

Checked 2026-09-26

What 64 means on this model

The power factor correction circuit has reported a fault. That circuit corrects the current the unit draws from the supply so that it runs close to unity power factor, which is what keeps the current low and the unit within its supply limits, and a fault here is therefore a supply side and board level fault rather than a refrigerant one. The service reference names this code as the active filter or PFC circuit, so treat the two as one circuit to test, not as two parts to guess between.

Symptoms you will notice

Code 64 and the system will not start
The system starts and stops quickly
The fault appeared after a power interruption or surge
The system runs in some conditions and not others

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 power factor correction circuit on the inverter board
A failed active filter component
A supply voltage problem such as a persistent overvoltage or deep brownout
A failed electrolytic capacitor in the DC bus
Board level damage from a surge

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.

Check the supply voltage and its stability, because a persistent overvoltage or a brownout will keep damaging this circuit even after a replacement.
Check for other codes alongside it, since the power and current codes travel with a power factor correction fault.
Confirm the supply meets the documented 198 to 264 V range.

Do not do these

×Do not replace the board without addressing the supply, because a supply outside range will destroy the replacement.
×Do not work on the DC bus or discharge it yourself. It can hold a lethal voltage after the unit is switched off.
×Do not keep restarting the unit.

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. This involves stored high voltage.

What it costs to fix

Parts

Inverter assembly or board $600 to $1,400. DC bus capacitor $80 to $250.

Labor

Three to six hours to diagnose and replace.

DIY or technician