problem: my car is always changing the fan speed, and this is really starting to annoy me, i have just gone thru the instruction manual and couldnt find any related info

(i have the climate control, not the manual knobs)

im pretty sure its speed dependent

eg: im driving normally, a/c on, fan on 2 bars. when i start slowing down for a red light, it automatically adjusts this to one bar. Then when i start to drive off again, it goes back up to 2 bars, or sometimes stays at 1 bar, i cannot figure out the logic

Is there someway to disable this stupid feature so I control the fan speed completely ?

There are also occasions when the fan speed just ramps up to 4 bars! and once again, i have no idea for the logic of when or why the system chooses to do this