Question Guys,
1999 silverado 2500 6.0l. I noiticed this summer that a weird noise coming from the left front area when using the a/c almost like a pressure relief going off (like a ssshhtt sound it's had to discribe) it last for only a second but does it ever couple of minutes now that winter is here this weekend i noticed it doing the same thing when defrost is on could it be a bad a/c compressor? It only does it when a/c or the defroster is on. If you shut the heater off it stops making the noise.The a/c work great it freezes you out so i know it's not low on charge.

My truck does the same thing but not very often. If you are not having any problems with the AC system, I wouldn't worry about it.

well since its a chevy, i am beting your ac is on during defrost. check your ac vent and see if its getting clogged. your ac system will cycle durning the winter.