Seal the balcony, put the air conditioner on the balcony, and make a box of cement on three sides, o

No, no, the air conditioner is a key component of heat dissipation, you seal it on three sides, how can the heat be taken away through the air, just like a hair dryer, you block the end of the air intake, how can the hot air come out? So you have to leave a ventilated air gap or hole in the back of the air conditioner. Let the air enter smoothly and take away the heat exchanged by the air compressor.

If you ask this question and add a picture, it is enough to see that you have concerns about heat dissipation in this solution. You put it together for the sake of sound insulation and dust prevention, but this will inevitably affect the function of heat dissipation.

Of course, there is a better solution, which does not affect sound insulation, dustproof, sealing, or heat dissipation, that is, sacrificing space and making a larger cement box for the air conditioner. Leave plenty of room to "inhale".

There should be no noise problem if it is sealed with cement and slate, so as to avoid the air conditioner dissipating heat into the room, and putting some potted plants on the slate will not affect the appearance.

The key is to make the vents facing the outside slightly larger.