Does my indoor air conditioner have to be replaced just because my outdoor AC unit goes bad?LegacyAc绝对不是. If this is ever suggested to you as a necessary thing, we suggest you thank the technician for his time, 打电话给另一家公司. The only exception to this rule is if your indoor unit is say an older model 10 SEER & you are moving up in your SEER rating at your outdoor unit. Problems can begin to occur when you mismatch ratings on equipment. We always recommend that you try and match the SEER ratings from inside to outside.