when I shut of vehicle it sounds like pressure is releasing any help would be great

 

where is the sound coming from?

 

from engine compartment

 

I am new to chevy trucks it kind of sounds like the same sound when you turn your wheel to far

 

A lot of different parts are under pressure. You have to locate where under the hood it's coming from. Find someone to shut it off for you while you get under the hood. If you can't find it then at least record a video with your phone and post it up.

Have you been losing coolant? Does your A/C work?

 

ac works great not loosing anti freeze .but that is the second time I heard anti freeze would that release preesure like that

 

I take it back ac doesn't work

 

The A/C system is not really something the backyard mechanic can work on. You need expensive tools to leak check or pressurize, so best to take it in.

 

know my 2002 was leaking around the high pressure sensor in the compressor itself. but it wouldnt leak sometimes, it pretty much blew out all at once. does your clutch engage when you call for ac? if not then you shouldnt hear anything as the system isnt being pressurized.