XSARA 1.9 TD air conditioning

Hello everyone. I have a Citroen Xsara 1900 turbodiesel, my problem is that the air conditioner has stopped working, I give in command and does not mention neither noises nor of anything. I would like to know if it can be a reliable or fuse and how to check it before leaving me the salary of the month in the workshop

First of all you have to have some manometro to verify that it has gas then if it has gas to look for the fuses if they are good or light it and with a current tester check if current arrives at the coil