Air Conditioning - Hot upstairs / Cold downstairs

We have a 50-year-old cape cod house we've been in for almost 2 years. Upstairs is our bedroom, which is almost always 15 degrees hotter than the basement, and 5-10 degrees hotter than the 1st floor, where the thermostat is. We have central air. It seems like the air doesn't even make it up to the upstairs. It doesn't blow hard from the register - but it doesn't with the heating either. Right now I have a fan on the floor in front of the register in an effort to suck the cold air up. I have all of the downstairs registers closed, and the first floor mostly closed. The furnace is only 3 years old, and I change the filter monthly.

I know I should get an attic fan for one thing, but don't have the money for that right now. There is no access to our attic space, so we'd have to cut through the plaster walls and then repair them (it's plaster, not drywall). I've already thought that I should get a solar powered one so I don't have to run electricity to it. Honestly though, I question whether it can possibly help that much. There are gable vents on each side and 2 static vents (I just looked up attic ventilation to know what to call them).

I'm working on getting more shade on the roof, but growing trees is slow. Right now the back half of the roof is in full sun most of the day.

I've got an idea -- tell me if this is crazy -- and if it won't work, why not.

There is a straight path from the basement through the back of a closet on the 1st floor to the bedroom wall on the 2nd floor. Couldn't I could conceivably run a duct from the basement to the 2nd floor, with a fan (like a register booster fan - see http://www.improvementscatalog.com/product.asp?product=49254zz&dept%5Fid=10120) on the top to pull the cold air from downstairs directly to the upstairs? I've seen something about return air flow being messed up (or something along those lines that I didn't quite grasp)? If it matters, We have huge return vents upstairs in both rooms.

If this is a descent idea, do I need to use ducting material (metal)? I was wondering if something (more inexpensive maybe, and easier to work with) like the flexible hose used for dryer exhaust would work.

We've got a break from the heat the past couple of days and for the next few, but wow - going to bed in a room that's 89 degrees really got to me more than I thought it would!

Thanks!

The first thing you need to do is have a competent A/C designer determine if your unit is sized improperly. That old of a dwelling makes it susect right off.

Then, gain access to your duct work. The air is going somewhere and you need to find out where. Your attic could be nice and cool in the summer and comfortably warm in the winter.

Beyond that determine if your unit is operating a peak efficiency, then either live with the results or consider upgrading.

Of course, that's JMHO.

You need two units! One for upstiars and one for down!

Have you tried the furnace blower on 24/7?
You could rework the duct for aa new feed to go up in the closet. BUT BUT. Code--- any duct from the furnace and going up that way has to be in metal or the fiberglass ductboard.

ED;)