Iam the biggest fan of a properly running R-12 a/c system, since you have already converted to R-134a, there is another trick to try, either bleed off about 12oz of the R-134a or evacuate the system and recharge with all but about 12oz and top off the system with "Cooltop" alot of people are impressed with the performance difference, It cost's a bit more than R-134a but you will only need one can.