Ya, agree with Anglefish. Happen to me also because the lable on the inlet and outlet was swapped. Because of this swap, the temp sensor was sensing the temperature of the outlet of cooling coil. As you can imagine, the temperature became very unstable. Hence, the compressor was cutting in and out very often, like every 2 minutes! Once I swap the lines (ensure the thermocouple is sensing the inlet into the chiller), everything works fine!
HTH.