GM Service Manual Online
For 1990-2009 cars only

Air Conditioning Evaporator Thermal Expansion Valve Description for Pontiac Firefly (Canada) 2000

The expansion valve regulates the flow of liquid refrigerant into the core of the evaporator. As the condensed liquid refrigerant travels through the expansion valve, the refrigerant pressure decreases considerably. As the pressure drops, the refrigerant temperature drops. The refrigerant that is passing through the expansion valve changes from a high-pressure liquid with a medium-temperature into a low-pressure liquid with a low-temperature.