It's the battery all right--4-5 years is a life expectancy for an OEM battery. The reason it starts with A/C off is there is less draw.
All this is based on my humble opinion only.
A few times in the last few weeks I'll go to start the old 99 and I'll get
> all the dash lights but nothing, no turn over. Then I'll wait a seconds and
> perhaps turn off the ac / fan and she'll start up. I think this is the > battery?
>
> I've never replaced the battery in this car and as I said it's a 99. Is that
> a normal battery life span? and if so what type of new battery should I get?
>
> How come batteries don't last forever, I figured because of the charging
> system batteries would last forever.
>
> Thanks for the info.
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