A Different AC noise

A DIFFERENT A/C NOISE?
I know there’s a thread on something similar but mine is different.
Sometimes I’ll here a noise when the a/c is on .. not all the time just a couple of times when I’m standing out side the truck with the a/c running the best way I can describe it sounds like a swamp cooler pump when the water level has gotten to low. Its not a slurping sound but more like the droning sound you’d here from inside the house when you know it needs water. A/c is cold , temp doesn’t fluctuate, it doesn’t “pulsate” to the sound in any way and I’ve only noticed it a few times. Other times I’ve been wiping my truck down real quick with a/c and everything sounds normal. When the charging system is low does it make a sound or just warm air? Cause that sound does sound like something is low but it’s not consistent enough and I know if I take it in it will be fine. I have the 100k extended warranty so I at least want it documented when I take it in for an oil change in case later it turns into something I’m covered. It’s a needle in a haystack but this forum is the home of serious Tacoma drivers so I always post here before I go in. Saves time and money. Thanks for any input bros