How to see if the hotel air conditioner is on?

Listening to the sound of the external machine, the sound when the compressor starts is different from that when the external fan rotates. The fan is whirring and the compressor sounds a little stuffy. Listen to the sound of the internal machine. When the compressor starts, it will sound like water flowing. Except when the air conditioner has no refrigerant. Measure the current. After the compressor is started, the current should reach at least 3A.

Feel whether the iron sheet of the external machine is hot or not. Don't touch the side facing the sun. After the compressor starts 15 minutes, the shell will heat up. Unplug the wire from the fan of the external machine and listen to the sound. If so, the compressor has been started. Feel whether there is cool wind at the air outlet. If so, the compressor has been started. Except when the air conditioner has no refrigerant. Touch the thin tube of the connecting pipe of the external machine and feel that the cold compressor will start. Except when the air conditioner has no refrigerant.