My ac light on mitsubishi endevor is off and it is not working

Do all the climate control functions work correctly (fan speed and vent selection)? If so the issue has to do with the A/C circuit. You can check the fuse first but You may need to send it in for diagnostics. Your vehicle was in production between 2004-2009. Usually I check the A/C for leaks, confirm that the correct amount of 134A is present and then check components under the hood first. A bad compressor or A/C clutch, bad connection or pressure sensor will shut the system down. Please let me know if this is what you were looking for.

Probably the ac low on R 134 gas,you need to connect tool and read the pressure ,this will give the reading ,I think you need to add gas and the ac will work,all the best.