< Also the system is not cooling that good as before. What do you think?
>

As I said, I think you may be overcharged.
Accurate low aux. fan pressure switch diagnosis requires high side gauge readings/measures.
And accurate system charge should be done by weight, although gauges and experience will work well.
One can use eyesight and fan activation to get it close , but if you have a bad switch, that technique is out and system pressure readings are the only [ and correct ] way to verify sw cut-in/cut-out specs....

__________________
A Dalton