noob a/c question....

[integra4991]

So I was under the hood of my truck tonight looking at the best way to run wires and such for my new gauges. Being an hvac guy by trade I grabbed the suction line on it and to my surprise it was cold. I knew the truck wasnt in a/c but i went and check and it was on the floor/dash vent. I played with different settings and found when on full dash or full floor its off and in off its off. This is my first ford and my first diesel as well, am I cracking up or is this normal?