'95 Sport 90 - A/C Compressor ticking/flapping upon engagement

["Mark W. Byrum, Jr." <markbyrum@erols.com>]

Ladies/Gentlemen:
	Recently had a/c recharged at independent Audi/Mercedes/Porsche dealer
with symptom of not significantly cooling.  Upon return of the car, the
dealer reported no fault found with system, so (he reported) they put
vacuum on same for about an hour, then fully recharged.  Cooling much
better upon return.  Repair ticket only notes 1.5 lb freon used.  No
problems for about 3 weeks.  Now, upon engaging a/c, I get a ticking,
knocking, flapping sound from compressor for the first 30 - 60 sec. 
Know its the compressor because when I turn off the a/c the noise stops.
	Isn't there supposed to be some sort of oil or other lubricant put in
along with the freon to ensure the compress does not destroy itself? 
Can this be checked somehow without going back to the dealer first?  Am
I destroying the compressor by using the a/c if lubricant was not added
by the dealer?  Any and all comments and suggestions appreciated.
	TIA,
	markbyrum@erols.com