Armored Core 6 Smart Cleaner: Weak Points & Build

Short answer: the EC-0804 Smart Cleaner has exactly two weak points — the glowing mouth on its front and the inside of the chimney on its back. Everything else is heavily armoured and takes almost no damage or impact. The official Armored Core VI Pilot's Manual (p.144) lists its defences as 930 kinetic / 351 energy / 1,000 explosive — energy defence is about a third of explosive, so energy weapons go through cleanly.

The single most useful fact: this boss has almost no anti-air. If your legs can stay airborne, you can shoot down into the chimney nearly unopposed.

Boss data

Picking between the two weak points

• The front mouth is easiest to hit right after the boss finishes an arm swing. The shutters and jaw on either side block shots, so you need a deliberate, aimed shot rather than spray.
• The chimney interior is visible when you look straight down into it. The chimney shaft itself blocks shots from shallow angles, so get close to directly overhead.
• The two weak points are separate lock-on targets. It is easy to have the wrong one locked, especially right after the boss leaves and re-enters your view.
• Do not rely on vertical missiles. The ceiling here is low, so they fail to arm unless fired from ground level, and even then they rarely drop cleanly into the chimney.

Attacks and how to handle them

• Two-armed crush — near-fatal on a clean hit. The recovery afterwards is your best window.
• Single-arm sweep — it tracks through roughly 45 degrees, so stepping slightly aside is not enough.
• Alternating arm thrusts — it advances a long way while doing this. Reset your spacing rather than trying to hold ground.
• The arms always have a damage hitbox, even outside an attack animation. Touching one knocks you into the other, and you can get chained between them for a long time. Do not try to hug its front.
• Chimney eruption — triggered by getting close to the chimney. A point-blank full hit deals heavy damage and guarantees a stagger on you. Do not perch on it.
• Molten spray — if you stand in front, it backs away and sprays molten metal from its mouth. The pool it leaves does damage over time, so move out of it.

The phase change at half AP

At roughly half AP the boss changes form: it raises both arms, triggers a large eruption, then slams both arms down. In the second phase it also opens up lava pools.

The phase change exposes the red weak point, but do not read that as a free opening — closing in gets you caught by the eruption. Secure safe footing first, then fire.

Stagger, and why there is no pulse armour step

A stagger leaves it standing still for a long time. You need to stay on it until just before it recovers, but there is room for two charged Pile Bunker hits. At that rate two staggers are enough to finish its AP.

Unlike Balteus, the Smart Cleaner has no Pulse Armor layer. Neither the official material nor the major guide sites list one; its defence is positional — everything outside the two weak points is simply hard. So there is no "strip the PA first" phase. You concentrate impact on the weak points from the opening second, which is what makes this fight assemble differently from Balteus.

Recommended assembly

1. Take a stagger-builder in the hands. A light linear rifle or a plasma rifle accumulates impact quickly, and energy damage benefits from its comparatively low Anti-Energy Defense.
2. Bring a finisher. The Pile Bunker fits this boss specifically because two charged hits realistically land during a stagger.
3. Missiles on one shoulder to maintain stagger and clear the trash on the way in.
4. Grenade cannon or laser cannon in the last slot. Both deliver impact and damage; pick by preference.
5. Account for the approach. "Infiltrate Grid 086" puts two enemy ACs (Invincible Rummy and Nosaac) and heavy MTs before the boss. A pure boss loadout runs dry before you arrive.

Leg types

• Tetrapod — hovering top-attacks are easy; lock the chimney and just watch your EN. But the corners of the arena have objects suspended from the ceiling that you can snag at altitude. Getting stuck, running out of EN and landing in front of the boss is a real way to die here.
• Reverse-joint — QB and jump cover the arm swings at long range, letting you work both the mouth and the chimney as the situation allows.
• Biped — bracing halts your descent, so you can hold position and keep a laser cannon firing into the opening.

The Chapter 5 rematch is a different fight

The Smart Cleaner reappears in Chapter 5's "Destroy the Drive Block", but it is not the mission objective there. The objective is destroying all the large skyrmion generators across the Xylem drive block; the Smart Cleaner is one enemy among the defending force.

Rusty (Steel Haze Ortus) fights alongside you in that mission, and an Arquebus Balteus is stationed in the same area. Do not approach it the way you approached the one-on-one in Chapter 2.

Why two different defence numbers exist

Sources state this boss's defences in two incompatible formats. Neither is simply wrong; they are different presentations.

Both agree on AP (48,705) and Attitude Stability (2,600). Only the defence representation differs.

This guide uses the raw manual values, for two reasons. They are the primary source, and the percentages do not reconcile internally: -7% kinetic matches 930 measured against 1,000 exactly, but applying that same baseline to 351 gives -65%, not -28%. There is no derivation that produces -28%, so this guide does not assert it.

The conclusion is unaffected. Energy defence is the clear outlier either way, so energy weapons are the ones that go through.

What this guide does not cover

• Weak-point damage multipliers. That non-weak-point hits barely register is observable, but no multiplier is published
• The exact AP threshold for the phase change. This guide says "about half" because that is as precise as the sources get
• Per-attack damage values

Sources

• Armored Core Wiki (Fandom): EC-0804 SMART CLEANER — cites the official Armored Core VI Pilot's Manual p.144 for AP, Attitude Stability and the raw defence values
• ARMORED CORE VI official: update notice, 18 September 2026 — used to confirm App Ver. 91 / Regulation Ver. 1.09.1
• Armored Core 6 Wiki (Fextralife): EC-0804 SMART CLEANER — designation, 48,705 AP, 2,600 Attitude Stability, weak points. Lists defences as percentages (see below)
• ARMORED CORE Wiki: AC6 Missions, Chapter 2 — mission data, attack patterns and leg-type tactics
• ARMORED CORE Wiki: AC6 Missions, Chapter 5 — "Destroy the Drive Block" objective and defending force