Heat on floor mode, A/C compressor kicks on/

I recently purchased a 2005 Monte Carlo, it has the 3.4l V6. I live in Pa. and like others our winter has been real cold, I was waiting to pick up my wife from work the other day, while sitting in the car i was changing the heat selections from defrost to floor to bi-level and realized that the A/C compressor clutch is engaging when the selector is on defrost and floor, it disengages on bi-level. I know that it is supposed to engage on defrost. Is it normal for this car to activate the A/C on floor? if so it is a first for me.
Thanks in advance for any input to this matter.

That is correct the A\C is used to dry the warm air. W/O the A/C you would get warm damp air.

Defrost and floor is still defrost so yes the AC compressor still engages. I have talked to many people who actually unplug the compressor in the winter months to stop the AC from engaging. Personally I see no difference. My other car has the AC removed and I drove it in winter many years and the defrost worked great.

If you unplug your a/c you run the risk of your windows fogging up really bad and fast

If you unplug your a/c you run the risk of your windows fogging up really bad and fast

As I already pointed out I ran without the AC plugged in on my Stealth for at least 8 winters with ZERO ill effects. The AC on my base Eclipse I had back in the day didn't work and the defrost worked excellent with ZERO ill effects. My Bronco II didn't have AC and the heat and defrost worked excellent with ZERO ill effects.

Many, many people unplug their compressor in the winter, again, with ZERO ill effects.