Correct A/C Pressures Double A/C Unit

hello all, i want to know wich is the correct A/C gas pressure for one 1991 Grand Caravan Dual A/C unit.. both side's low & high
by the book please,i dont want guesing.. have to be perfect ..


Thanks all
Att
Alf..

Ideal pressures are 40 psi low side, 250 psi high.