We recently purchased a 25 year old house and the A/C doesn't sufficiantly cool the second floor. The basement and first floor cool OK. The Heating/AC equipment is original(25 yrs old) and we recently had a company come and take a look at it. He said the first issue was that there was a belt driven motor on the furnace which was not powerful enough to reach the second floor.

He suggested replacing the furnace and condenser first, as opposed to installing a second A/C unit in the attic, since we may have to replace these things in the next couple years due to their age. He thought that with new equipment, the problem may be better, may not solve it completely, but certainly would be better. I'm not sure which is the better route. Any Suggestions?

Cooling second floor levels with basement units can always be an issue. First problem is that heat rises and the upstairs can be the warmest part of the house. Sometimes you can close some of your downstairs registers and this will increase the static pressure forcing more air to the second floor providing you have registers on the upper level. If you only use the second floor at night, it would be more efficient to install a separate unit in the attic that you only need to run at night and then increase the set point on the downstairs unit thermostat to save energy.

Your system has seen its life go with a new system and add zoning to the duct work. One system that acts like three independent systems.