air ride does not work how do you check that the compressor is good?

air ride rear suspension on a 1997 buick lasabre with 101000 miles cream buff is not working how do you troubleshoot it to see if its the compressor adjusting linkage or wiring is bad I feel confident the shocks are bad but not sure and I dont want to replace them until I am confident the compressor and all components are or can be repaired by myself if not I will just go out and buy heavy duty shock because I use the car to trailer 2500 pound tag along camper