thats evaporation and heat causes it
evaporation
The change from the liquid state to the gas state is vaporization (boiling) or evaporation.
A change of state from a gas to a liquid is called condensation.
a phase change: solid to liquid: melting liquid to solid: freezing liquid to gas: vaporization gas to liquid: condensation solid to gas: sublimation gas to solid: deposition
the correct term is condinsation for the change of state from gas to liquid
The refrigerant change of state is what causes the heat transfer. The refrigerant is a low-pressure liquid when it's in the evaporator, which absorbs heat from the air, cooling it. The absorption of the heat causes the refrigerant to boil (change state from liquid to gas). The gas is then brought to the condenser in the front of the car where it cools (rejects heat out) and condenses back to a liquid.
In a word, temperature. A physical change will change the matter's state based on it's temperature. For example, water, H2O. You can increase the temperature to 212oF and it will change state from a liquid to a gas. You can decrease the temperature to 32oF and it will change state from a liquid to a solid. To answer your question, the process of doing so would be increasing or decreasing temperature of matter.
The change from liquid to gas at the surface of a liquid is known as vaporization.
The change in physical state from a gas to a liquid is called condensation.
If a liquid was to boil to change state, it would be changing from a liquid to a gas, and would be said to be boiling.
condensation
A change in state can be caused by either adding or removing energy from a substance. For example, adding heat can cause a solid to melt into a liquid, and removing heat can cause a liquid to freeze into a solid. Pressure changes can also cause a substance to change state, such as turning a gas into a liquid by increasing pressure.