Toyota Repair: 2005 Rav4 air conditioning problem, clutch assembly, toyota factory

Question
hi- my AC will work for about four minutes, then the light begins to blink, and it quits cooling.  We had the codes read at the Toyota place, and it showed no codes at all.  
They want to replace AC clutch assembly, but they are not totally sure if this will fix it.  Your opinion on this? The repair guys seem unsure of themselves, and this is an expensive repair to experiment on.
thanks-

Answer
If it has less than 36,000 miles the repair is still covered under the toyota factory warranty, if it's out of warranty and they are not sure what to do or if what they recommend may not fix the problem I would get another opinion at another dealer if possible, it's not that hard to diagnose if a compressor is at fault or the clutch or something else so I would agree that they are unsure and I would not go ahead with any repairs unless they can guarantee the problem will be fixed right the first time, otherwise they are willing to guess and gamble at your expense.