Yaris 2 D4D 2009 without AC serpentine belt

[rasyaya]

After removing all A/C components, I removed the A/C amplifier (unit under the dashboard) as I thought it will not be necessary anymore. But I had to put it back because I realized that without it my blower motor speed is unstable. In fact, it speeds down when I touch the gaz pedal, and goes back to original speed when I let go the gaz pedal. I also noticed that when it has speeded down (foot on gaz pedal) and I turn on the headlights, it speeds up to its original speed. All this happens only when I am driving not stopped.
This is weird, since the A/C amplifier is not supposed to control the blower motor speed . Does it have a current regulation role that might explain what happens without it?
Has anyone tried removing it or encountered the same issue?

PS : Since I plugged the AC amplifier back everything went to normal, so it is not an alternator or battery problem...