1998 Ford Contour rough idle when i turn my air conditioning on

Rough idleing, especialy when the air condition is on, is really quite normal for old cars. I drive a 96 corolla and when the airconditioner is turned on, the car will make a deep whining noise. It should stop when shifted into drive(automatic) or gear(manual) in most cases, it is not a serious problem. However, if you feel the idle is too rough, i would recommend fuel additives designed for highmilage cars. I use fuel injector cleaner. after many uses, my rough idle ended. If after trying this, you find the idle to still be to high or rough, have a talk with your local mechanic. Hope this helps