Groaning 98 3.8 Windstar

[Rdana]

When I shut off the engine,there is a noise that sounds like a balloon stem being stretched and the air escaping.it starts from the passenger side of the engine(around the evaporator) and ends under the van at the rear heater/ac unit. It lasts for 6-8 seconds and is loud enough for others to hear when I turn it off in a parking lot. It is driving me nuts. Any ideas??
Thanks Bob

 

[martin]

Sounds like a leak in the vacuum controls for the heater.