Learn Hardcore Indonesian: Cuaca sangat dingin; bahkan AC dimatikan. - The weather is very cold; even the AC is turned off.

Active: mematikan (to turn off [something])
Passive (agentless): AC dimatikan (the AC was/is turned off) This passive-without-agent is very common in Indonesian when the doer is unknown, unimportant, or obvious from context.

How would I say who did the action (e.g., “they turned off the AC”)?

Several natural options:

Active: Mereka mematikan AC.
Passive with agent: AC dimatikan oleh mereka. (grammatical, a bit heavier)
“Short passive” with a pronoun agent: AC mereka matikan. (very natural in speech) Pick active if you want to highlight the doer; pick passive if you want to foreground the object/result.

Can I say AC mati instead of AC dimatikan?

Yes, but the nuance changes:

AC dimatikan = an action was performed (someone turned it off).
AC mati = the state/result (the AC is off/not working). No mention of who did it. Use the action form when you care about the turning-off event; use the state form for the current condition.

What does -kan add in dimatikan?

Suffix -kan often marks a causative or makes a verb transitive. From mati (off/dead) you get:

mematikan = cause something to be off (turn off)
dimatikan = be caused to be off (be turned off)

What does bahkan do here?

Bahkan means “even,” introducing a surprising or extreme example. It emphasizes that turning off the AC is an unexpected consequence given how cold it is. It doesn’t mean “instead”; it’s an intensifier of degree/surprise.

Where can I place bahkan in the clause?

Common, natural placements:

…; bahkan AC dimatikan. (as given; strong emphasis)
…; AC bahkan dimatikan. (emphasis sits more on the verb phrase)
…; AC-nya bahkan dimatikan. (with -nya for definiteness) Starting a new sentence is also fine: … Sangat dingin. Bahkan AC dimatikan.

Should I add pun (e.g., bahkan AC pun dimatikan)?

Pun adds “even/also” emphasis. Options:

AC pun dimatikan (natural, emphatic)
Bahkan AC pun dimatikan (possible, very emphatic; some find it a bit redundant)
Bahkan AC dimatikan (already clear and common) Use pun when you want extra heaviness on the surprising item.

Why a semicolon? Could I use a period or comma?

The semicolon links two closely related independent clauses without a conjunction. Alternatives:

Period: Cuaca sangat dingin. Bahkan AC dimatikan. (clean, common)
Comma alone is less standard; if you want a smoother link, add a connector: Cuaca sangat dingin, sampai-sampai AC dimatikan.

Is sangat the only way to say “very”? What about sekali or banget?

All are common with different tones:

sangat dingin (neutral/formal)
dingin sekali (neutral; sekali comes after the adjective)
dingin banget (colloquial) Avoid terlalu dingin if you just mean “very,” because terlalu means “too (excessively) cold.”

Should it be cuaca or udara here?

Both are acceptable, with nuance:

Cuaca = weather (broader conditions). Cuaca sangat dingin is fine.
Udara = air. Udara sangat dingin highlights the feel of the air/temperature. In everyday talk about how it feels, udara is very common; cuaca is also natural.

What does AC mean in Indonesian, and how is it pronounced?

AC refers to an air conditioner (not “alternating current” in this everyday context). Standard Indonesian pronounces the letters as Indonesian letter names: A-CE (roughly “ah-cheh”). A more descriptive term is pendingin ruangan, but AC is by far the most common.

When should I use -nya as in AC-nya?

-nya often marks definiteness (“the”) or “its/his/her.” Examples:

AC-nya dimatikan = the AC (that one, in this place) was turned off.
AC-nya sudah mati = the AC is already off. Attach -nya with a hyphen to abbreviations: AC-nya (not “ACnya”).

How do I show tense/aspect? Does dimatikan mean past?

Verbs don’t change form for tense. Time/aspect is shown with particles/adverbs:

Completed: AC sudah dimatikan.
Just now: AC baru saja/tadi dimatikan.
Future/intended: AC akan/akan segera dimatikan.
Habitual: Sering AC dimatikan malam hari.

Is there anything to watch out for with di in dimatikan?

Yes. The passive prefix di- is attached to the verb: dimatikan (no space). The preposition di (“at/in/on”) is separate and followed by a location: di rumah, di kantor.

What’s the opposite of mematikan/dimatikan for devices?

Turn on (active): menyalakan (e.g., menyalakan AC)
Be turned on (passive): dinyalakan (e.g., AC dinyalakan) You can also describe state with hidup (on/alive): AC hidup = the AC is on.