Santa FE SM (2001-06) :: 2004 - AC Noise Every 30 Seconds But Air Still Works

I have an Air Conditioning issue on my 2004 Santa Fe, 2.4L 5-speed manual with 208,000km on it. I've never had any work done on my AC since I bought it new. Never had a problem with it and even as I write this is works just fine and blows ice cold air.

The problem started a couple of weeks ago when I noticed this very brief "higher pitched burping sound" coming from under the hood that lasts for just a second, and only when the AC is on and only if the RPM's are above idle. It sounds like a "bloop" for lack of a better description. When it happens, the RPM's drop one mark on the RMP gauge for a moment and there is obvious strain on the compressor. Air remains ice cold, everything still works, but this occurs every 30 seconds or so while driving.

While stopped I can rev the motor to just above idle, say 2000rpm and engage one of the defrost settings and get the "bloop" sound to occur almost every time. The top thicker AC pipe leading into the firewall from under the hood (the one that gets cold to the touch) seems to be part of the problem. At least if I am touching this pipe when it makes this "blooop" sound I can feel the vibration from the "bloop" in this pipe.

I've already had a garage replace my AC belt which I just had replaced a month ago, and checked the pullies and tension and all is okay. So it's definitely coming from the AC system and I can feel a vibration during the "blooop" sound on that pipe that gets cold and goes through the firewall. The sound does not occur when the AC is not on.

Also, when I am driving and it occurs every 30 seconds I do feel a slight decrease in the smoothness of the ride and like I said when it does this the RPM's will drop one mark on the gauge, which I'm assuming is the strain on the motor trying to engage the compressor when it's probably already up to pressure.