Heating AC and Engine Cooling
Air Conditioning and Coolant
Heating Ventilating and Air Conditioning
iPhone 3GS

When you turn OFF your automobile with the ac on why is there a boiling hissing kind of sound from the evaporator for 10 seconds or so?

Answer

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Wiki User
03/27/2008

that is the sound of the refridgerent pressure equalizing itself throughout the system. it is perfectly normal.