Cooling on ideal model 55b

I have a old Dr Pepper Ideal model 55b. The compressor has the flared screw on fittings. Is the valve on this the low side that you add the freon. And what should the low side reading be. This unit has the cooling in the walls. The compressor runs and the condenser fans runs, but it will not cool. This machine had been sitting for serveral years before I got it. Is this a job I should turn over to Eric?
      Thanks,
    Tommy

Ideal Model 55B Dr Pepper (working on)
2-Cavalier 64Js (working)
cavalier C6 (working)
Cavalier CSS 141G working under carport(Changer will just go to 25 cents) loaded with 12 oz plastic coke & dr. pepper bottles, also drinking water bottles
Cavalier CS 191 (working)
Cavalier 96J(working)
Vendo F83 needs restoring
Vendo H126 needs restoring

[MoonDawg]

If one of your tires is flat one morning, you can fill it with air but if you don't find the leak the same thing will occur. That is true here also, the freon leaked out.
      Have a  local refrigeration company put your system under a pressure test, find and repair the leak and then recharge with R-12.