Refrigerant Flow

Refrigerant Flow
During stabilized (A/C system shutdown) conditions, refrigerant system pressures are equalized on both the high and low sides of the refrigerant system.

When an A/C, mix or defrost function is selected and vehicle requires cooling, the system operates as follows:
- The A/C clutch field coil is energized and the A/C clutch is pulled into contact with the belt-driven A/C clutch pulley.
- The A/C clutch then rotates the compressor shaft.
- When the A/C compressor shaft is rotated, the refrigerant vapors from the suction side of the refrigerant system are compressed into a decreasingly smaller area, increasing the refrigerant vapor pressure and also raising the refrigerant vapor temperature.
- The high-pressure and high temperature A/C compressor discharge refrigerant vapor is released into the A/C condenser core assembly through the A/C manifold and tube.
- In the A/C condenser core, high pressure refrigerant vapor condenses into a high pressure liquid when heat is removed from the refrigerant vapor by outside air passing over A/C condenser core fins and tubing.
- High pressure liquid refrigerant from the bottom of the A/C condenser core enters the inlet side of the A/C evaporator core orifice.
- Refrigerant pressure is reduced in the A/C evaporator core as a result of the flow restriction produced by the A/C evaporator core orifice and the A/C compressor suction.
- As passenger compartment or outside airflow passes over the plate/fin sections of the A/C evaporator core, the refrigerant inside absorbs the heat and changes into a vapor.
- A/C compressor suction draws the vaporized refrigerant and oil mixture into the suction accumulator/drier where the heavier oil-laden vapors fall to the bottom and the lighter vapors and oil mixture continue their path to the A/C compressor through the A/C manifold and tube.







Refrigerant Systems
These vehicles offer the R-134a A/C system.
- The R-134a system uses a non-chlorofluorocarbon (non-CFC) based refrigerant R-134a.
- R-134a is a hydrofluorocarbon (HFC)-based refrigerant.

The A/C refrigerant system is a clutch-cycling, orifice-tube type. The system components are as follows:
- A/C compressor
- A/C clutch
- A/C condenser core
- A/C evaporator core
- suction accumulator/drier
- necessary refrigerant lines

System operation is controlled by the following:
- A/C evaporator core orifice
- A/C cycling switch
- A/C compressor pressure relief valve
- A/C pressure cut-off switch

The refrigerant system incorporates an A/C compressor controlled by an A/C cycling switch.

The A/C cycling switch:
- senses A/C evaporator core pressure to control A/C compressor operation.
- controls the compressor to stop compressor operation during ambient temperatures below approximately 10°C (50°F) and to prevent A/C evaporator core from icing during normal system operation.

An A/C compressor pressure relief valve is installed in the A/C manifold and tube to protect the refrigerant system against excessive refrigerant pressures.