Refrigeration System

The refrigeration circuit of the climate control system is changed from the previous VIR (valves in receiver) system. The new system is called a CCOT (cycling clutch with orifice tube) system.

The main changes are the elimination of the expansion and POA valves along with the VIR assembly.

In the earlier VIR system the A/C compressor ran continuously and the expansion and POA valves controlled the flow of refrigerant to and from the evaporator.


In the COOT system a simple orifice tube (fixed restrictor) meters the flow of refrigerant to the evaporator. The A/C compressor is now cycled to control evaporator pressure and temperature.






Refrigeration Cycle
The compressor discharges high pressure refrigerant vapor that contains heat absorbed in the evaporator plus heat created by the compression process.

The vapor then flows through the condenser where it releases heat and turns into a high pressure liquid. This liquid then flows to the expansion tube, which is a simple fixed restrictor.

The expansion tube meters the amount of refrigerant into the low pressure evaporator where the refrigerant vaporizes and absorbs heat from the passenger compartment.

Under high heat load conditions all of the liquid is vaporized in the evaporator. Under lighter load conditions some of the refrigerant remains in a liquid state. The liquid and vapor are separated in the accumulator so that only vapor flows to the compressor. The remaining liquid will then slowly vaporize and also return to the compressor.