Air conditioning: Refrigerant

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2007 Volvo V70, 2006 Volvo V70, 2005 Volvo V70, 2004 Volvo V70, and 2003 Volvo V70. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Principle Sketch Of Climate Control System

Courtesy of VOLVO CARS OF NORTH AMERICA.

Compressor
Condenser
Engine cooling fan (FC)
Receiver drier
Expansion valve
Evaporator
Blower fan.

Explanation:

A - High pressure, warm fluid

B - Low pressure, cold fluid

C - Low pressure, cold gas

D - High pressure, warm gas

Dark arrow - Warm air

Light arrow - Cold air

By allowing the refrigerant to circulate in the closed system and changing the pressure and volume it will change temperature and boil (evaporate). At the pressure found in the system, approximately 170 - 320 kPa (1.7 - 3.2 bar), the refrigerant boils at approximately 0 °C to +4 °C.

A condition of the refrigerant boiling is that the heat is accessible. This heat is taken from the air around the evaporator (6) where boiling occurs. When the heat is taken up by the refrigerant the surrounding air becomes cooler. It is this cooled air that is blown into the passenger compartment by the climate control system blower fan (7). The heat taken up by the refrigerant in the evaporator (6) is transported out to the engine compartment, where it is transferred to the air by the condenser (2). The condenser is cooled by the airflow and the engine cooling fan (FC) (3).