AC V-belts keep slipping

Hallo from the Netherlands.

I have a Gates v-belt for my AC. But I
think I have to tighten it way too much. It keeps sliping sometimes.
So is there is a better v-belt than this or another option.
AC works fine.

Thanks.

 

How do you know it’s slipping?
Does it squeal?
Your AC maybe overcharged, AC pump pulley going out, or the pump itself causing higher than normal load

 

Yes. It's a New aluminium A6 pump with singele groove. With the old Stock A6 pump same problem.
So is there another option. Other brand v belt or another kind v belt.

 

Remove the belt, spin the pulley by hand, then engage the clutch, rotate the compressor by hand.

 

You may have too much refrigerant in it. What pressures are running at 1200 rpm? 1500 rpm?