Odd sound when A/C or defrost are on

I noticed this first when it was still warm enough for the A/C to be on, and now it happens when you turn the defrost on, when the system is just on heat, but not defrost, the sound doesn't happen, when you do hear it and either turn off the A/C or defrost, it stops immediately.
I have not been at my house for a few months, it started maybe 2-3 months ago, and now that i am back where i have my tools, i'd like to get this fixed.

This recording is from inside the cab, i can get one from outside under the hood if it would help.

Im thinking it has something to do with the compressor as that is the only thing that would be coming on and turning off that would correspond with the sound.

I am not sure how to upload sound files, when i tried the upload a file button it said this was a unsupported file type, so i linked it from my personal site. You may have to turn up your volume, cause it isnt very loud, i also turned on and off the system a couple of times so you could hear it starting and stoping to make sure you knew what you were listening for.
http://timstinkerings.com/?attachment_id=238

Edit to add a google drive link for the sound file
https://drive.google.com/open?id=0B7tWt4LwXk5raV9CeUpSRi1Lb3M

 

Sound clip didn't work for me but I too would have to say it's pointing to the compressor

 

If it's just your compressor coming on that's normal. Well - on newer vehicles it is. When you run the defrost it will kick on the AC compressor. Dry air defrosts faster. Also helps circulate the AC system in winter months to keep the system lubricated.