Common 16V Air Conditioning Failure Points?

[steiner_ca at hotmail.com (Craig Steiner)]

What/where is the common failure point for the 16V air conditioning system?  
I've had 2 separate technicians look at it in the past, and they couldn't 
find the problem.  First guy put in the dye to find leaks.  None found.  
System even held a vacuum after any remaining R12 was evacuated.  Second 
tech converted system to R134a (free of charge) and it worked for about 2 
weeks.  I know most people just rip out the system, but has anyone had 
success in getting it to work again?

Thanks,
Craig

Enid, Oklahoma
'88 Alpine White 16V