Yes!
No you don't have to change the A/C Compressor.
newer vehicles, such as a 99 jeep, all use 134-A refrigerant.
R134a
No use R22. R134A is for automotive applications.
r134a
It compresses the refrigerant (probably r134a) and pushes it through the ac system.
With proper retrofit... Yes
You are low on refrigerant, google R134a...
too much oil in system or compressor not working properly are some possibilities
See a specialist. System needs to be purged, leak checked & Recharged.....
No. Simply will not work