'10Q7TDI_Prestige'

Scan the car fully for errors. You need to do the leak-down testing to determine if you have any residual, small air leaks as a result of cracking open/removing the air lines, or from those corner check-valves located on each damper, etc.

He suggested to replace the valve-block at same time, as the compressor and the valve-block are the two primary components of the air suspension, and they are co-located in the carrier assembly, etc., which is being proactive since complex parts don't last forever. If you plan on keeping the car long-term, then it makes good sense just to go ahead and replace both at same time. This is especially true if car has the optional running boards mounted on it, which complicates gaining access. Bottom line; if money is not a problem, you are better off replacing the old parts. Do the testing for air leaks, regardless of if you swap the valve-block or not.