The repair person was here to look at my AC unit. It needs an a- coil and the since the unit is 8 years old he suggestion I might want to think of a getting new unit. If I do decide to get a new unit, do you think I need to also replace the gas furnace. Thanks for any guidance.

How efficient is your furnace. Is it a 80% or a 90% unit in good shape? If not you may consider replacing the furnace also. Naturally if you have the cash laying around there is nothing wrong with getting a new furnace and A/C. In most cases like this I just replace the A coil add a filter dryer pull a good vac and run the older A/C and furnace unit till it really has bigger problems. I say this assuming that your outside condensing unit is OK.