Vent/Floor mode question

[neil]

My 2005 has manual control temp and vent selection. I've noticed that when I turn to vent only (one position left of the 12-o'clock off position) and vent-floor (one position right of the 12-o'clock off position)...I get the A/C pump cycling. This is when I'm asking for heat.

I'm familiar with why you want the A/C pump cycling for defrost with heat (or cool)...but why the A/C pump with vent or vent/floor?

It does not cycle with floor only. Can this be programmed out of the logic of the truck? I don't want the A/C pump cycling unless I'm calling for A/C or defrost.