The a/c system is protected by safty switches. (High and Low)if the system is low on feon it will not turn on. Check your a/c hose's, if any are sweaty with oil or the connections have dirt built up around them, then you have a leak and should be fixed. Most system's just need a recharge after 6 years. The compressor shaft seal is the one point that will not hold pressure for this amount of time. If not sure please check with someone who is qualified to work on the system, just to be sure it's not low.