Learn Hardcore Turkish: Vantilatör açılınca oda serinledi; herkes sohbetine döndü. - When the fan was turned on, the room cooled; everyone returned to their chat.

The suffix -IncA (spelled according to vowel harmony as -ınca/ince/unce/ünce) forms a time clause meaning when/once/as soon as. So aç-ıl-ınca = when it is turned on. The vowels harmonize with the last vowel of the stem: after a back vowel like a in aç-, you get -ınca.

Why is it açılınca (passive) and not açınca (active)?

Because the fan is not the one doing the action; someone turns it on. Açılınca is passive: “when it is turned on.” If you want the active version with an (implicit) human subject, you’d say: Vantilatörü açınca oda serinledi. (“When [I/you/one] turned on the fan, the room cooled.”)

Can I use açıldığında instead of açılınca?

Yes. Açıldığında (“when it was turned on”) is very close in meaning, slightly more formal or explicit. Both are fine: Vantilatör açılınca / açıldığında oda serinledi.

What does the semicolon do here? Could I use something else?

The semicolon links two closely related independent clauses (cause → result). A period would also be fine: … serinledi. Herkes sohbetine döndü. You could also use ve (“and”) if you want a looser link. A comma between two full clauses is less standard in formal writing.

Is herkes grammatically singular or plural?

Grammatically singular. It takes a 3rd‑person singular verb: herkes döndü, not (formally) döndüler. In colloquial speech you may hear plural agreement, but the standard is singular with herkes.

What exactly is happening morphologically in sohbetine?

It’s sohbet + i + ne:

-i = 3rd‑person singular possessive (“his/her/its conversation”)
-e = dative (“to”)
n is a buffer consonant between the two vowels.
So sohbetine = “to his/her conversation.”

If it refers to “everyone,” why not the plural possessive (sohbetlerine)?

With quantifiers like herkes, Turkish typically uses the singular possessive but understands it distributively. Herkes sohbetine döndü = “Everyone returned to their (own) conversation.” To make that explicit, you can add kendi: Herkes kendi sohbetine döndü. Plural -lerine fits with a plural pronoun like onlar: Onlar sohbetlerine döndüler.

Why does dönmek take the dative here? Do I need geri?

Dönmek takes the dative to mean “return to X”: X‑e dönmek. Geri (“back”) is optional emphasis: sohbetine döndü vs sohbetine geri döndü. For activities/topics, the dative alone is perfectly natural.

Can I say sohbete döndü instead of sohbetine döndü?

Yes, but the nuance changes.

Sohbetine döndü: returned to his/her own conversation (possessive, distributive with herkes).
Sohbete döndü: returned to chatting/the conversation (generic, no possessive).

Why serinledi and not serinleşti or soğudu?

Serinlemek: to cool down, become cooler (often experiential; fine for a room too).
Serinleşmek: to become cool(er) (focus on the transition/state change).
Soğumak: to get cold.
All can work; serinledi suggests it became pleasantly cooler, serinleşti is a bit more neutral/formal, soğudu is stronger (colder).

What tense are serinledi and döndü?

Simple past (-DI), indicating completed events the speaker presents as definite. If the speaker were reporting without direct evidence, they might use the inferential past: serinlemiş; herkes sohbetine dönmüş.

Can I move the time clause or change the word order?

Yes. Turkish is flexible with subordination and topic–focus. Examples:

Vantilatör açılınca, oda serinledi; herkes sohbetine döndü. (original order)
Oda serinledi, vantilatör açılınca; herkes sohbetine döndü. (time clause after)
Vantilatör açılınca herkes sohbetine döndü; oda serinledi. (different focus)
Word order tweaks shift emphasis, not core meaning.

Does açmak mean “open” or “turn on”?

Both. Açmak is “to open” (a door/window) and “to switch on” (a fan/light/TV). The passive açılmak is “to be opened/turned on.” The opposites are kapatmak (to close/turn off) and kapanmak (to be closed/turned off).

Is vantilatör the same as ventilatör? Any pronunciation tips?

Vantilatör usually means a household fan.
Ventilatör tends to mean a medical ventilator (though usage can overlap).
Pronunciation: ç = “ch,” ö like German “ö,” and dotless ı is a central vowel (like the unstressed ‘e’ in “taken”). So açılınca is roughly “a-chɯ-lɯn-dʒa.”