my 2014 Acadia's air conditioner not working well

A/C system should be bought to a pro , the parts are designed to work together at certain densities and pressures

If charging the system did not fix the problem, you likely have another defective component like the condenser or compressor. Are you sure that you properly performed the recharge? Also, did you check for proper belt tension? At this point, it may be time time bring it to a competent shop.