Cheri, make sure #5 fuse isnt blown. I thinks for the compressor. If it is blown, its due to a faulty airpump clutch. Which over loads that circuit and blows the fuse. If thats ok, could be the klima relay/which controls the ACC system. Its located in the fuse box a black large relay in the rear its says klima right on it.
But then again like all the other guys say. If your hoses are leaking the system is dry and the compressor wont kick on.
keep me posted
FACTORY TECH MB 14 YRS