What does the owner of a car experience after the engine is shut down with the A/C running?

When the engine of a car is shut down while the air conditioning (A/C) system is still running, the owner typically experiences normal noise caused by fluid pressure equalizing. This phenomenon occurs as the refrigerant pressure in the A/C system stabilizes once the engine is turned off. The noise heard is often due to the transition of refrigerant from high pressure to lower pressure levels as it moves through the system. This pressure equalization is a normal part of the A/C operation and does not indicate a malfunction.

In contrast, a broken or leaking vacuum hose is not a typical experience after engine shutdown with the A/C running. While vacuum hoses can indeed malfunction, such behavior would present different symptoms while the engine is running and not specifically related to the action of shutting down the engine with the A/C still operational. Thus, the noise of pressure equalizing is the characteristic and expected sound in this scenario.