Dear Tom and Ray: A few summers ago, the air conditioner on my 1993 Dodge Caravan went out. The cost to fix the unit (from two different sources) is $1,700 to $2,000. The car is not worth that much, so I have not fixed it. Last week, while walking through a Home Depot, I saw a portable, stand-alone air conditioner on sale for $595 (you can see where I'm going with this ...). The unit requires a 115-volt connection to operate it. Can I get an adapter at Radio Shack, buy the rolling air conditioner and plug it into my cigarette lighter? I know other appliances can be plugged into the lighter, but I'm not sure the car can accommodate the demands of an air conditioner. Ignoring the fact that I will look like a hillbilly, what do you think?John

Tom: Well, at least you'd be one cool hillbilly, John.

Ray: It can be done, John. But there are a number of conditions. The first is: Forget about the cigarette lighter. That'll give you enough juice to power your cell phone or your glow-in-the-dark Parker Posey dashboard ornament. But you'll melt it if you try to run a major appliance through it.

Tom: You need a device called an "inverter," which is a box that converts DC power into AC power. You'd have to run special wires from the inverter right to the car's battery.

Ray: We checked with our inverter expert, Don Rowe, and he has two recommendations. One is that you find a small, efficient, 5,000-BTU air conditioner. Fedders and Daewoo make such models, and they only cost about $100 at home centers.

Tom: And even though those units use only 575 watts of continuous power, they do "surge" when they kick in, demanding nearly twice that much power. So Don recommends that you go with an inverter that provides 2,000 watts continuous/4,000 watts peak power. That'll run you about $250.

Ray: I believe the V-6 Caravans came with either a 90- or 120-amp alternator, which should be sufficient. Anything less than 90 amps, though, and you'd have to spend a few hundred bucks to have a heavy-duty alternator installed. Otherwise, you'd be stopping for gas, an oil check and a new alternator every 200 miles.

Tom: And then the final question is how to install the AC. If it were me, I'd just pop it in the passenger window. You know, hold it at the top and roll up the window until the unit is good and tight. It'd provide a good laugh for other drivers on the road!

Ray: No, you can't do that, for safety reasons. You'll have to find some way to install it permanently, John. The hot air and condensation need to escape, and fresh air needs to be drawn in.