differential setting

[hantstwo]

what setting should the differiantial be at on a reach in display cooler ranco 01-1418 control its used for dairy

[hantstwo]

i forgot its R12 the bulb is reading ambient near the evap my background is hvac my customers handyman messed it up ican't find any suggested settings

[maxgeyer]

pressure settings are 10 psi out ,,,,35 psi in
hope that helps
temp in fridge should be min= 3 degrees c ,,, maximium= 7 degrees celsius