Electrical problem

While driving down the road my alternator light comes on. It stays on 95% of the time. Periodically the brake light andairbag liget comes on and the lights get brighter and the A/C either stops cooling or if it keeps cooling the fan blows faster. It stays on for a while then just goes off. The lights go out on their own without hitting a bump or anything. The alternator is less than 6 months old. I had the alternator checked and I also pulled the positive battery cable off while the alternator light was omni and engine keeps running. Any suggestions?