a/c problems

Have a 1998 3.8L mustang and I am having a/c problems. It was working o.k then the other day it started blowing warm air. The compressor is kicking on for abut 5 seconds then goes off. It continually does this. Can anyone give me a heads up on were to start problemsolving. Would like to check things out my self before bringing it into a shop. Will be checking my freon charge today.

sounds like low freon,possible leak or could be low pressure sensor located on evap/dryer.You can try to jump the 2 terminals by unplugging the connector,see if the compressor comes back on after going off,if ti does,you prolly have a leak,fords were always bad for o-ring leaking