Depressurizing noise after turning '02 off

[Sammy323]

Help! Every time I turn off my '02 Mountaineer I hear a noise from under the hood like something is depressurizing. It is a low level moan that lasts for about 3 seconds. Could it be the breaking system or perhaps the power steering?

Performance of the car doesn't seem to be affected, but I would like to stop the noise so the clients don't hear it. Thanks in advance for your help.

 

[Merc02]

maybe some type of vacuum leak. Check all your lines, start at the charcoal canister. I've never had trouble with mine, I don't know where it is.

is your check engine light on, if so take it to auto zone and let them read the error codes for free.

 

[Minivek]

Check your fan as the engine is stopped, it seams the viscous clutch makes a groaning hissing sound and the fan spins down.... You could also check the overflow tank cap to see if its leaking pressure...

 

[Minivek]

Did you find out what it was?

 

[puum]

My '03 makes the same noise and has for years. Or I'm betting it's the same noise. My assumption on mine is it's the IAC valve. But it's just a minor annoyance so I haven't had the ambition to do anything about it.