With a unit in that mid-age it might be worth the money to have them find and fix the leak. Don't know what UTC's warranty was on those units back then, so I would check to be sure you don't have at least a parts warranty still active.
If it is determined you need a new outdoor unit you may be able to just replace that and reuse the indoor coil and possibly the lineset, depending on age, SEER rating, how much you use your A/C. Regardless, there is no reason to replace your furnace.
If it is determined you need a new outdoor unit you may be able to just replace that and reuse the indoor coil and possibly the lineset, depending on age, SEER rating, how much you use your A/C. Regardless, there is no reason to replace your furnace.