Forget about the sub cooling with refrigeration. It is what it is. With a TXV your going to want to know what the superheat is. This is a cooler correct ? If the coil is at 20-25 degrees that would be correct for a 10* TD evaporator.
when i get there ill recover the 134a and change the txv while iam there to make sure its not the problem and check subcooling again lol and i wish i new the factory charge but it cant no more than 12oz with 1/4hp
The model # you gave is for the condensing unit. It may or may not be the original. Your charge will depend on several other factors. Unless you have worked on a piece of commercial equipment since it was new, you have to start at the beginning.