1993 Jeep Cherokee Problem with alternator

This is perfectly normal on older alternators. If yours is original to the car or has seen an excessive amount of use it is just the brushes wearing out, you can rebuild the alternator if you can find the parts, though Jeep alternators are cheap enough it might be worth your while to just buy a new one or re-man.

Also, it is not critical to change it right away as when you rev the engine it kicks in so for normal driving this won't be a problem, just keep in mind when you start it that you need to rev it a little and you'll be fine for a while.