The Refrigerant Cycle
| Item | Description |
|---|---|
| 1 | Evaporator temperature sensor |
| 2 | Evaporator |
| 3 | Cabin Thermostatic Expansion Valve (TXV) |
| 4 | Cabin Thermostatic Expansion Valve (TXV) Manifold and Tube Assembly |
| 5 | Cabin A/C Isolator Solenoid Valve |
| 6 | A/C charge valve port (low side) |
| 7 | A/C charge valve port (high side) |
| 8 | Condenser with integrated receiver drier |
| 9 | Receiver drier |
| 10 | High Voltage Battery Coolant Cooler |
| 11 | High Voltage Battery Coolant Cooler Thermostatic Expansion Valve and Isolator Solenoid Valve Assembly |
| 12 | High Voltage Battery Coolant Cooler Thermostatic Expansion Valve Manifold and Tube Assembly |
| 13 | A/C Low Pressure Sensor |
| 14 | A/C High Pressure Sensor |
| 15 | A/C Compressor to Condenser Discharge Line |
| 16 | ACCM (Air Conditioning Control Module) |
| 17 | High-pressure liquid |
| 18 | Low-pressure liquid |
| 19 | High-pressure vapor |
| 20 | Low-pressure vapor |
During stabilized conditions (A/C system shutdown), the refrigerant pressures are equal throughout the system. When the electric A/C compressor is in operation, it increases pressure on the refrigerant vapor, raising its temperature. The high-pressure and high-temperature vapor is then released into the top of the Air Conditioning A/C condenser core.
The A/C condenser, being close to ambient temperature, causes the refrigerant vapor to condense into a liquid when heat is removed from the refrigerant by ambient air passing over the fins and tubing. The now liquid refrigerant, still at high pressure, exits from the bottom of the A/C condenser and enters the inlet side of the A/C receiver/drier. The receiver/drier is designed to remove moisture and contaminants from the refrigerant system.
The outlet of the receiver/drier is connected to the Thermostatic Expansion Valve (TXV). The Thermostatic Expansion Valve (TXV) provides the orifice, which is the restriction in the refrigerant system which separates the high and low pressure sides of the A/C system. As the liquid refrigerant passes across this restriction, its pressure and boiling point are reduced.
The liquid refrigerant is now at its lowest pressure and temperature. As it passes through the A/C evaporator, it absorbs heat from the airflow passing over the plate/fin sections of the A/C evaporator. This addition of heat causes the refrigerant to boil (convert to gas). The now cooler air can no longer support the same humidity level of the warmer air and this excess moisture condenses on the exterior of the evaporator coils and fins and drains outside the vehicle.
The refrigerant cycle is now repeated with the A/C compressor again increasing the pressure and temperature of the refrigerant.
A thermistor monitors the temperature of the air that has passed through the evaporator core and controls electric A/C compressor speed. If the temperature of the evaporator core discharge air is low enough to cause the condensed water vapor to freeze, the electric A/C compressor reduces it speed.
The high-side line pressure is also monitored so that electric A/C compressor operation will be interrupted if the system pressure becomes too high.
The low-side line pressure is also monitored so that electric A/C compressor operation will be interrupted if the system pressure is determined to be too low (low charge condition).
The electric A/C compressor thermal protection switch will interrupt compressor operation if the compressor housing exceeds temperature limits.
The A/C compressor relief valve opens and vents refrigerant to relieve unusually high system pressure.