Если кондиционер сломается, включи хотя бы вентилятор.

Russian has no articles, so words like the and a/an are not translated directly.

So:

• кондиционер can mean the air conditioner or an air conditioner
• вентилятор can mean the fan or a fan

The exact meaning comes from context. In this sentence, English would most naturally use the if both people know which air conditioner and fan they mean.

Russian works differently from English here. After если, Russian can use a form with future meaning very naturally.

Сломается is the perfective future of сломаться, so it means will break down or ends up breaking.

So:

• Если кондиционер сломается... = If the air conditioner breaks down...

English often avoids will after if, but Russian does not follow that same rule in the same way.

They come from different aspects of the verb:

• ломаться = imperfective
• сломаться = perfective

In this sentence:

• сломается means breaks down / becomes broken as a single completed event
• ломается would usually mean is breaking, keeps breaking, or malfunctions in a more ongoing or habitual sense

So Если кондиционер сломается focuses on the moment when it stops working.

This is an aspect question again.

• включи = perfective imperative
• включай = imperfective imperative

Включи is used when you want one complete action:

• Turn on the fan

It fits this sentence because the speaker wants the person to do one specific thing if the air conditioner breaks.

Включай would sound more like:

• turn it on / be turning it on
• a repeated, ongoing, or more process-oriented instruction

So включи is the normal choice here.

Включи is the singular informal imperative. It is used when speaking to:

• one person
• in an informal way

So the sentence is addressed to you singular, like talking to a friend, family member, child, or someone you speak to with ты.

If you wanted the polite or plural form, you would say:

• включите хотя бы вентилятор

Russian often omits subject pronouns when they are obvious from the verb form.

Here, включи already shows:

• it is a command
• addressed to one person informally

So ты is unnecessary.

You could say ты включи хотя бы вентилятор, but that would add emphasis and is not the neutral default.

Хотя бы means at least or if nothing else.

So:

• включи хотя бы вентилятор = turn on at least the fan

It suggests:

• the air conditioner may not work
• the fan is not the ideal solution
• but it is better than nothing

It often adds a slight feeling of compromise:

• at least do this much

It is in the object case: accusative. But for many masculine inanimate nouns, the accusative singular looks exactly like the nominative singular.

So:

• nominative: вентилятор
• accusative: вентилятор

That is why the form does not change.

Compare with an animate masculine noun, where accusative would look different:

• Я вижу брата = I see my brother

But:

• Я вижу вентилятор = I see a/the fan

Russian normally uses a comma to separate a subordinate clause from the main clause.

Here:

• Если кондиционер сломается = subordinate if-clause
• включи хотя бы вентилятор = main clause

So the comma is required.

This is standard Russian punctuation with если clauses.

Yes. Russian word order is fairly flexible, though different orders change the emphasis.

The given version is neutral:

• Если кондиционер сломается, включи хотя бы вентилятор.

Other possible orders:

• Если кондиционер сломается, хотя бы включи вентилятор.
• Хотя бы вентилятор включи, если кондиционер сломается.

These alternatives can sound more emphatic or conversational. The original sentence is a very natural, standard way to say it.

Кондиционер means air conditioner.

In everyday Russian, it usually refers to:

• an air-conditioning unit
• a room air conditioner

So in this sentence, it means the cooling device may stop working, and the speaker suggests using a fan instead.

Yes, the main stresses are:

• кондиционер
• сломается
• включи
• хотя́ бы
• вентилятор

A learner-friendly breakdown:

• если кондициОнер сломАется, включИ хотя́ бы вентилЯтор

Getting the stress right matters, because Russian stress is mobile and not always predictable.