I see you're learning spanish too. I'm native spanish, and I can tell you that you'll find this same phrase in Spanish too... it means "va y viene", I mean, it's works randomly: sometimes it works fine, sometimes it doesn't work, sometimes it works poorly... it isn't stable :)
To understand that, I take into account what is the point of reference. "Comes and goes" if it comes is because it was gone. If a dive is supposed to be on constantly then you would notice the problem because it "goes and comes".
The opposite is applicable: if the device is supposed to be off most of the time and you just turn it on to used at specific moment then you would notice that it does not work at all or that it "comes and goes".
The heating in my appartment have dual aspects. Let's say I have the heating on the whole day during winter and then the Super of the building starts turning service on and off during the day. From this point of view I would day that heating "goes and comes". That is because it was supposed to be on in the first place then I noticed the problem when it stared "going and coming".
Now let's say it's the end of the summer / beginning of the winter. The heating (the service provided by the landlord) is suppoed to be off. But during the week the Super of the building has been turning on and off the heating. Then I would say "the heating has been coming and going the whole week".
Same thing when one says "back and forth", "in and out", etc.
This is what observe and understand. Similar to Spanish
Irse e Venire -Go (away) and come (back)- refers to the suspension and reactivation of certain services like electricity (often called "corrente" or "luce") and water. You might hear "la corrente si va ogni giorno alle otto e viene alle undici" Everyday the light goes (away) at 8:00 and comes (back) or returns at 11:00. This is, everyday the electric service is suspended at 8:00 and reactivated at 11:00. "La luce va e viene ogni giorno a la stessa ora, da cinco a sette dalla mattina".
Ire e venire (go and come) refers to the functioning of something. "Il ricalentamento va e viene" (the heating -referring to the heating system- goes and comes). That is, it stops working and then starts working again.
Considering the lengthy discussion this has caused, perhaps this sentence should be moved to the idioms lesson. Can we all just agree that idioms are the way they are through tradition and traditions are regional and cultural. Romance languages do it one way, English the other. (I don't know if it extends to other Germanic languages. Any German speakers?) It's not unusual for English to be opposite of everyone else. Look at how the English insisted on driving on the left side of the road for no other reason than the French use the right. LOL Although, it also has something to do with one's sword arm.
Judging by the number of posts saying it didn't make sense and it should be "on and off" suggests many highly intelligent people would differ. When this many people are confused, I usually stop blaming the people. The heating, whether it's "comes and goes" or "goes and comes", suggests on face value that your heater it getting up and leaving the house, only to return when it's finished its errands. I see your point that there are many idioms that are much more baffling. But, I guess it's a matter of degrees. How "opaque" does it have to be to qualify? Is "translucent" good enough? ;-)
The complaints come from a solidly English-language sense that the words "on" and "off" need to come in a certain sequence. I don't think I've seen anyone say they don't understand what it means, just that they don't understand why it's said slightly differently.
An idiom would be more along the lines of "Non vedo l'ora". Literally, it says "I cannot see the hour". Can you guess from this that it's used to mean "I can't wait"?
In this case, it's a matter of that's not how the expression works. Just because you can use the simple present or the present progressive in general doesn't mean they mean the same thing and isn't always appropriate in all contexts.
The expression "the heat comes and goes" is always in the present simple. It means "sometimes the heating works right and sometimes it doesn't".
"The heat is coming and going" sounds off to me as a native speaker of Midwestern American English. It's not something that can be happening right now. It's the general overall state of how the heating functions.
@Rostellan I'm not a moderator, but I might be able to help. Translation is as much an art as a skill. It would behoove you to give up on always finding a direct translation. Especially, with sayings and idioms.
"It goes" is plain, basic, vanilla, present tense. The funny thing is, we English speakers don't speak in present tense as often as one might think. We often use the gerund, as in, "It is going." It would sound strange to an English speaker to say, "Ok, I go now." We would use the gerund, "I am going."
However, speaking in present tense isn't strange in romance languages, such as Italian. If we were to write the sentence above as a gerund, it would read: "Il riscaldamento sta andando e venendo."
But "comes and goes" or "goes and comes" sounds better to me, especially being a turn of phrase.
For the purpose of the exercise and getting it right, "goes and comes" is correct and word for word like Rae says. But translation is an art more than a science. I'm pretty sure most English speakers say "comes and goes". At least my NE American matches my British wife in this respect.
This is a case where the idiom differs between Italian and English, and so we need to reverse things to render it naturally in English. And in English, we say "The heating comes and goes". It means that it's not working the way it should; it's kind of broken. Sometimes it works okay and sometimes it doesn't. And this kind of thing sounds rather odd in the continuous aspect. It makes it sound like the on-again-off-again is all happening right now in this very moment rather than being a general description of how it works.
Plenty of people say "comes and goes". Like me.
And "goes on and off" does not mean the same thing as "comes and goes". The former refers to it cycling on and off normally. The latter refers to when something goes wrong and sometimes it functions as it should and sometimes it doesn't.
"Comes and goes" is definitely the preferred form in English. I would expect from this example that the Italian equivalent of "goes and comes" is more natural in Italian.
These things develop in part because of how it sounds to say two or three words in a phrase. This has to do with cadence (the rhythm of the phrase) as well as sounds that get stuck together in a certain order, and which word sounds best as the final word in the phrase. (The other day I was trying to put together three words in a set ("a, b, and c") and considering which order they should go in, and it did seem that the sound of the final one mattered a lot more than the other two.) And since you can't expect both words to sound the same in Italian as in English, you can't expect the phrasing to be identical.