Third A.I.R. Pump in 4 months

I just installed a new AIR pump this weekend for the third time since August. I am beginning to wonder if an underlying problem. Parts come from Xcel, this is AC/Delco replacement, Cardone, so it shouldn't be cheap auto parts store crap. Do not yet have shop manual therefore not understanding what I am reading concerning Diverter valves and check valves in the "AIR" system. Any ideas on what to check and how? The pumps are seizing up, I assume from overheating.