Suspension problem
2002 Buick Lesabre 6 cyl Front Wheel Drive Automatic 158000 miles

This car is a Taxicab in Denver, Co. Recently had new auto load leveling rear air shocks replaced. Now I am told the exhaust driven compressor is allowing the shocks to bleed down overnight.

Is there any reason to believe this may be due to faulty installation of the new shocks and air lines?

Is there any acceptable repair short of replacing entire compressor unit for $700.00 (I've already spent $500 for the shocks).