My GMC Sierra sounds like it has gas

My 2002 GMC Sierra, when the AC is on, occasionally makes a sound like pressure escaping from an air tank. Sometimes it doesn’t do it at all, like when I take it to the dealer to get fixed, and other times it does it every 30 seconds or so. It’s worse in hot weather, but I’ve had it do it in the winter when the Defrost (and AC) is on. It sounds like an Air Compressor that has a broken regulator and builds up too much pressure and releases the pressure. The sound only lasts for about 1/2 a second, but it’s fairly loud. It’s coming from under the hood, because it is very loud when driving slow with the windows down. It will do it at all speeds, and is very annoying. We’re planning on taking this truck to the Grand Canyon this summer, so I’m hoping to figure it out. My wife says we should just buy a new truck. Any ideas?

Seems cheaper to fix your truck versus buying a new truck. A new truck will set you back quite a bit and will lose a lot of value in the first year alone.

The AC system in your vehicle is called a CCOT system. Cycling Clutch Orifice Tube.

This means that the compressor cycles to a certain pressure then shuts off and then the orifice tube releases this pressure. This is what causes the cooling effect. If the the screen in the orifice tube becomes plugged all the pressure is forced thru the orifice tube itself and the AC can make this noise.

Replacing the orifice tube will fix this problem. But one has to worry what’s causing the screen on the orifice tube to plug up.


What could cause the screen on the orifice tube to plug up?

Debris from an AC compressor that’s wearing out. Here’s what the orifice tube looks like.