Found Prep Table unit running box temp OK. Rail not frosting across. Shut down box and ran rail. Rail calling for cooling but going off on low pressure. Installed pierce valves and found system low on charge. Leak checked and found low pressure switch cap tube rubbed thru and leaking. Installed temp switch and pinched leaking line. Will return in the morning to brake in new switch and access ports. 9/4/20 Installed new low pressure control and service ports. Held 110psi nitrogen. Pulled 500 micron vacuum and charged with factory charge and cycled OK.