So i shut off my car and notice a hissing sound, sounding like someone was letting out the air in my tires, i open the hood and saw nothing odd, it seemed like it was by the firewall of the car, not surewhat this could be as its the first i heard it, any insights?
Thanks

 

Can anyone help on this or explain? I didn't have my air conditioner on either since that is what i thought it was.

 

Could it have been maybe the fan? The fan keeps working if the engine is too hot to cool it down.

 

Could it have been maybe the fan? The fan keeps working if the engine is too hot to cool it down.

 

not sure, i just took it out now and did not notice it at all, just only noticed it this morning when i got to work and i turned off the car. The funny thing is is the car was off and it was doing this nosie...sounds like air is being taking out of my tires...

 

Some people have had leaks in he vacuum line going to the power brake booster. That line goes through the firewall. Next time it makes that noise, move that line around abit and see if it is the source.