the air-conditioning unit is put on the engine goes off

Yeah, unfortunately this is because your compressor is locked up and it is seizing the belt and the crank stops spinning.

Here are some guides that will help with this:

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

https://www.2carpros.com/articles/replace-air-conditioner-compressor

Below you will find the process from the manual that will help with this as well. Please let us know if you have other questions. Thanks