Learn French: Le technicien n'a pas encore testé la climatisation de la chambre. - The technician has not yet tested the air conditioning of the room.

In compound tenses like the passé composé, the negative phrase wraps around the helper verb. So, pas encore goes immediately after the auxiliary verb (a) and before the past participle (testé), giving us n'a pas encore testé. Unlike in English, you cannot put it at the very end of the sentence.

Doesn't encore usually mean "again" or "still"?

Yes, on its own, encore often means "again" or "still". However, when it is combined with ne... pas to form the set phrase ne... pas encore, the meaning shifts entirely to "not yet".

Is climatisation the most common way to say "air conditioning" in French?

While climatisation is correct and used in writing or professional contexts, French speakers very often shorten it to la clim in everyday conversation.

Could I use pièce or salle instead of chambre for "room"?

It depends on the type of room. Chambre specifically means a bedroom or a hotel room. If the technician were testing a generic room in a house, you would use pièce. Salle is usually reserved for rooms with a specific practical function, like la salle de bain (bathroom) or la salle de réunion (meeting room).