ONE ILL-placed air conditioner in a tiny Georgetown row house shared by four good friends, almost cooked my first Washington summer.

The culprit was in a far back bedroom only one big enough for one. (The landlord wouldn't let us move it.) Since I'd never experienced a Washington summer, I readily gave up my dibs on the cooler just to keep the peace.The others tossed for it. Frankie, our delicate Texas rose, won -- and promised to share when it got hot.

Sure. Each night after the dinner dishes Frankie disappeared into the luxurious coolness of her tiny bedroom -- shutting the door behind her. The rest of us were left dripping wet. We had to play "tenement" -- otherwise known as sitting on the front stoop, absorbing whatever cool breezes occasionally passed by.

Finally, one steaming night only Frankie could sleep. No matter how many showers we took, it was impossible to stay cool for more than 5 minutes.

"I've had it," Jody said. "I'm going in there."

"Wait," I cautioned her. "She won the toss fair and square. Moving in on her really isn't right."

"Well, if we can't move in with her," said the usually quiet Susie, "why not let her move back in with us?She said she'd share it with us, didn't she.

The three of us then quietly proceeded to remove the hinges from Frankie's door. The door came off easily. Its removal created a delicious cooling breeze. We laid mattresses across the entrance of Frankie's room. Frankie slept through it all and for the remainder of the summer even our tempers were cool.

Placement of an air conditioning unit is very important, as we found out that summer. Cold air drops immediately to ground level and pushes the hot air up. And cold air does not blow around corners.

If you're buying an air conditioner, be realistic. A large unit is not always better than two smaller units -- it depends where you place them and how large an area you're trying to cool. Every air conditioner dealer has a chart to tell you what model air conditioner is necessary to cool your size room or house.

Customer specialist Chuck Collins of General Electric says, "People think they're economizing when they buy a 10,000 BTU unit for a house whose size calls for 12,000 BTUs. But one large unit must work harder and burn more energy if it's required to cool off too large an area."

"And then," Collins adds, "there's the customer who gets annoyed when the air conditioner they bought for their 10-x-10-foot bedroom isn't cooling the room. What they forget to tell the dealer is that they're opening their bedroom door to cool the hallway and the bathroom too!

"If you want to cool a larger area it's a better idea to buy another unit," suggests Collins.

Before turning on your air conditioner, here are some important maintenance notes.

Check the air conditioner's filter -- the conditioner takes longer to cool when the filter is dirty. The filter traps dust, dirt, pollen and then airborne contaminants. Some filters need to be replaced periodically, others can be cleaned -- check your use and care manual. One filter cleaning per year is ample unless you run your conditioner 24 hours a day, in which case you'd have to clean the filter more often.

Remove the front grill of the conditioner (it should snap off) to reach the filter. Wash it in warm soapy water and air dry. If the filter needs to be replaced, a hardware or department store will sell a washable aluminum mesh filter that can be trimmed to the correct size with a scissors.

If your air conditioner has been in the window for 2 or 3 years check the condensing coils located in the back of the conditioner. The coils, whose job it is to condense the freon gas before it enter the compression chamber, often collect dirt and become clogged. The best way to clean the coils is to call the manufacturer and have them steam clean the entire conditioner -- the process can't be done at home. The charge for steam cleaning, which is not in most gurantees, is in the range of $60. However, if customers can bring the conditioner to the manufacturer, the saving is almost $40.

Walter Prokopik, manager of consumer relations at General Electric in Jessup, Md., says that you can also hose down the air conditioner in order to clean the coils. But you must be sure that the conditioners is completely dry before re-installing. Prokopik prefers the steam cleaning method.

Another important check point is the fan blades. Every air conditioner has one or two fans inside their motors to keep them from getting too hot. If the fan blades collect dirt, this forces the fan to work harder -- creating motor bearing problems. During the winter months, the dry heat from your home may cause the blades to crack. (For the last 15 years, fan blades have been made from plastic rather than metal).

To clean: use the brush attachment of your vacuum cleaner. Be gentle. The brush will prevent you from damaging the blades and various switching devices inside your conditioner. If the dirt is really caked on, wipe the blades with water or a very mild detergent. Wipe the detergent off with water and dry thoroughly.

General Electric's customer relations manager Collins recommends that customers check their conditioners instead of waiting until midsummer when something goes wrong. "What usually happens is that we remind our big apartment and hotel clients to check their conditioners now, but come July we get calls from customers who want our service -- yesterday!" Collins did say that service calls deceased last summer, since the 78 degree regulation went into effect.

A spokeswoman for Westinghouse stresses that the temperature outside should be at least 75 degrees or more, before turning on the conditioner. "People turn them on when it's 50 degrees and then can't figure out why the machine doesn't work." Pete Ruffini, a salesman with Westinghouse agrees: "If it's too cold out, you can ruin the motor system."

Ruffini recalls a baker who wanted to know "if he could run his air conditioner in the winter, since it got so hot inside his bakery. I told him that when its 32 degrees outside, an air conditioner won't do you much good. Cooling 32 degree air would freeze the conditioner."

To get the most out of your conditioner and save energy at the same time:

Keep the sun off the back of the conditioner -- install it in the shadow of a tree or bush. Too much heat makes the unit work that much harder.

Keep your shades and curtains drawn on the sunny sides of the house.

Operate all lights and appliances -- anything that generates heat -- at a minimum.

Close off areas where the cold air could escape, such as cold air ducts, hot air registers and chimney flues.

Keep windows closed.

Open doors as little as possible.

And remember to unplug your conditioner first, before doing any maintenance work.