You need to replace:

drier bottle - $64
expansion valve - $75,
pressure switch ($24),
temp switch ($20)

Then a flush, evac and charge - $60-80 is needed. Throw in two hours' labor for $130 and some ester oil and you're looking at right around $400 to do it right. If you don't do it this way, you will suffer because the system will not cool as well with the R134.

If you plan to keep the car for 2-3 years, this is a worthwhile investment.

My $.02

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe