Help Me With Weird Noise

[zonefive]

When the A/C is working I am hearing a pulsing noise every couple of seconds from the engine compartment on the driver's side. Sounds like it is near the bulkhead. And is soft, like a heartbeat. Very regular and about every 2 seconds or so.

Anyone have any idea? If it is some kind of pump I'd rather get it replaced now before it breaks.

TIA

[4.8isX5]

Can you get a video of what it sounds like? Much easier for anyone to reply then if they hear it on a video. I almost feel as if i know what your talking about, but for me i just think its a v8 thing and not on your 3.0

[danp]

Heater Valve. Mine does it as well. Never heard it before but since the cold has started and I am using the heat it does pulse. If you watch you will see the hose move when the pulse goes.

I got another one but not having any trouble with heat or ac right now. Anyone else advise as to the issue? Should I replace it?