When you have the a/c button de-activated, recirc on, and fan on, it will still cycle the compressor as if the a/c button was pushed ...
(you don't need to be in defrost for this to happen... it will happen on face, bi-level, and floor)
When in defrost mode, the compressor short cycles... (different)
The only way you can run recirc with no compressor cycling, is turn the fan OFF and hit the recirc button again, then the vents will all close off...
11H