What are the correct pressures with front and rear a/c?

95 Astro - temp @ 83 F
Both front and rear air on
low side @ 26
High side @ 120
Rear blows cooler air then front

Front air only
Short cycles
Low side 40 -> 18
High side 52 -> 100

Is this a case of low coolant or something else wrong?

95 i think has r134 at 85 deg ambient temp reading on low side is normal
high side is low should be in 200-230 could be low on charge or worn comprosser i would evac the sys and recharge with the correct amount
first.