Whooshing sound when turned off

[Britto96]

Hey all, I own a vy commodore (2003), my car has been overheating and needs a new water pump but I’ve just gone for a drive to woolies and back home (only 5 minutes drive) and after I turned my car off, I noticed it’s started making a whooshing sound under the bonnet (sounded like it was coming from engine) and I noticed a little bit of moisture on the front plastic part under the bonnet, it’s the first time my car has made this noise and I’m not sure what it could be, any ideas?

 

[krusing]

Sounds like the Air Conditioning system equalising.
Keeping in mind, it does operate under high pressure.

But it could be a lack of coolant due to the water pump you mentioned,
It could also be the coolant outlet pipe seal and/or o’ring that requires replacing, that may of leaked the coolant out, very common fault.