Toyota Repair: 1998 Sienna rear A/C, c lines, expansion valve

Question
I repaired a leak @ the rear A/C lines ('O' rings) and the A/C worked very well for about four days. Now the rear unit only blows warm air even though the front unit is still blowing cold. Could this be the expansion valve in the rear unit?

Answer
I would say that is a possibility, there can't be a leak because the front is still ok and both units use the same freon. Check the a/c lines underneath and see if the low side gets cold an the high side hot, if not there is a blockage at the rear evaporator.