Refrigerant System - Cycling Clutch Orifice Tube (CCOT)

The Cycling Clutch Orifice Tube (CCOT) refrigerant System is designed to cycle a fixed displacement compressor ON and OFF to maintain desired cooling and to prevent evaporator freeze-Up.

The refrigeration cycle (ON and OFF Operation of the compressor) is controlled by a pressure cycling switch that senses low side system pressure as an indicator of evaporator temperature. The switch is mounted to the side of the accumulator with a standard needle type valve.

With ambient temperature of 16-25°C (60-80°) and the system turned OFF, equalized pressure within the charged A/C system are sufficient to close switch contacts. When an air conditioning mode is selected, voltage is applied to the compressor clutch coil through the switch. As the compressor runs, low side (suction) pressure decreases and high side (discharge) pressure increases. When suction pressure drops to approximately 152 kPa (25 psi), the pressure cycling switch opens, de-energizing the compressor clutch. With the compressor stopped, system pressures again begin to equalize. When low side pressure reaches approximately 296 kPa (43 psi), the switch contacts close, the clutch coil energizes and the compressor begins to run. This cycling process continues and maintains evaporator discharge air temperature at approximately 3°C (38°F).

Because the clutch is cycled ON and OFF, some slight engine speed/power increases and decreases may be noticed under certain conditions.