Buying a bagged Custom 4Door Blazer! Help

Hey I am buying a bagged '96 four door blazer from a friend of mine. He hasn't driven it in years and its been sitting outside in his driveway. Everything works fine but I feel like I should maintenance the bag system, compressors? Can anyone point me in the right direction of what I should do? I also uploaded some pictures I have. I'll be updating more as soon as I get tags on it.