Bi12D

hi everyone,well my problem with my is350 is my radio works find but my a/c unit plus the radio display flickers on and off and sometime turn off all together but the radio still works.i checked all my fuse and put a test light to the each fuse and they all turn out good.its a base model radio,last thing i did to it was change my battery but this happen before i change my battery and still going on so i would like to know if anyone have this problem or do i just buy a used a/c unit,thanks