ac not very strong

If you are in the Eco driving mode, you might not be getting full AC potential. Try the power mode to see if you get more cold air.

 

If you are in ECO mode, turn it off. If it still does not cool well, get it checked out.

 

Try normal. ECO will take it down a notch.

 

Also, have you set the temperature down to a lower value, if your vehicle allows that?

 

Prius A/C is quite specific. I had the same feeling at the beginning. One thing is ECO mode. While this mode is activated maximum output power (and maximum fan speed) are trimmed down to conserve energy, especially on short trips. If you feel that you need to cool down fast switch to normal mode (A/C efficiency is the same in normal and power modes).
Another thing is when you have set A/C for example at 23 deg C and the in-car temperature is 25 deg C but you feel that fresh air or short cool air blow is needed, especially in spring or autumn. Then you have to step down temp 2 - 3 degrees for short time and then set them back to desired temperature.

If you set A/C to LO with A/C light ON and normal mode and still feel that it is not cooling as it should have it checked. A/C subsystem should be checked for leaks every two years. Maybe your is depressurised and not working effectivly (which may also damage A/C compressor due to lack of lubrication).

Mine did great job cooling down the car in the middle of the day (33 deg C outside) within 5 - 6 minutes to 24 degrees. Cold air was blowing from vents 30 seconds after start and working compressor was clearly hearable (much louder than ICE warmup).