c230k2005

I have a 2005 C230K with AC problem. There is refrigerant in the system since the static pressure is around 70 psi. However, when I press the AC on, the pressure on the low and high sides do not move at all. Therefore it must be the compressor not functioning. Anyone know how I can fix it? Is it the pressure/temp switch that is faulty or the compressor? Any help will be appreciated.