Installatøren sjekker innedelen så vel som utedelen.

The ending -en is the definite singular ending for many masculine nouns in Norwegian.

• en installatør = an installer
• installatøren = the installer

In this sentence, Norwegian uses the definite form because it is talking about a specific installer.

Norwegian often forms compound nouns by joining words together.

• inne = inside / indoor
• ute = outside / outdoor
• del = part, unit, section

So:

• innedel = indoor unit / inside part
• utedel = outdoor unit / outside part

Then the definite ending -en is added:

• innedelen = the indoor unit
• utedelen = the outdoor unit

Writing compounds as one word is very normal in Norwegian.

Here too, -en marks the definite singular form.

• en innedel = an indoor unit
• innedelen = the indoor unit
• en utedel = an outdoor unit
• utedelen = the outdoor unit

English usually uses a separate word, the, but Norwegian often adds definiteness to the noun itself.

Because in Norwegian, definiteness is often shown by an ending on the noun rather than by a separate word.

So instead of:

• the installer
• the indoor unit
• the outdoor unit

Norwegian says:

• installatøren
• innedelen
• utedelen

This is one of the biggest structural differences from English.

Sjekker is the present tense of å sjekke, meaning to check.

• å sjekke = to check
• sjekker = checks / is checking

In Norwegian, the present tense often ends in -er:

• snakker = speaks / is speaking
• jobber = works / is working
• sjekker = checks / is checking

Norwegian present tense can cover both English checks and is checking, depending on context.

Så vel som means as well as.

In this sentence, it links two things:

• innedelen
• utedelen

So it means the installer checks the indoor unit as well as the outdoor unit.

It is a bit more formal or careful than simply using og (and), though in many contexts the meaning is very close.

Yes, in many situations you could say:

Installatøren sjekker innedelen og utedelen.

That would mean The installer checks the indoor unit and the outdoor unit.

But så vel som puts a little more emphasis on the idea of both or as well as. It can sound slightly more formal or more deliberate.

This is standard Norwegian main-clause word order:

subject + verb + object

• Installatøren = subject
• sjekker = verb
• innedelen så vel som utedelen = object phrase

That is very similar to normal English word order:

The installer checks the indoor unit as well as the outdoor unit.

So this sentence is quite straightforward in structure.

The letter ø is a Norwegian vowel that does not exist in standard English.

A rough approximation:

• it sounds somewhat like the vowel in British English bird, word, or her, but with rounded lips

In installatøren, the ø is in the last stressed part:

• in-stal-la-TØ-ren

This is only an approximation, but it helps English speakers get closer.

Because the sentence is talking about the indoor unit and the outdoor unit as two specific individual parts.

So Norwegian uses singular definite nouns:

• innedelen = the indoor unit
• utedelen = the outdoor unit

If it were plural, the forms would be different, for example:

• innedelene = the indoor units
• utedelene = the outdoor units

Yes, very often. In technical or everyday Norwegian, innedel and utedel are commonly used for systems that have:

• an indoor unit
• an outdoor unit

For example:

• heat pumps
• air conditioners
• similar installation systems

So these are very natural compound nouns in that context.