Traditional Culture Encyclopedia - Hotel franchise - There are three vents at the top of the hotel room. How to distinguish between air outlet and return air?

There are three vents at the top of the hotel room. How to distinguish between air outlet and return air?

Air return, air outlet and inspection port;

When the air conditioner is turned on, the wind comes out of the air outlet;

One of the air intakes is the air return port, and the other is the maintenance port;

If the air conditioner can't be turned on for a while, open the access door (there is no air outlet grille) and judge which return air and which air outlet from the structure of the air conditioner.

Generally a square is a manhole.