1997 Chevrolet Suburban Owner's Manual - Page 86

Engine Coolant Heater (Option) In very cold weather, 0°F (- 18 C ) or colder, the engine coolantheater can help. O To Use the Coolant Heater 1. Turn off the engine. 2. Open the hood and unwrap the electrical cord. 3. Plug it into a normal, grounded 110-volt AC outlet. - /!\ CAUTION: Plugging the cordinto an ungrounded outlet could cause an electrical shock. Also,the wrong kind of extension cord could overheat and cause a fire. You could be seriously injured. Plug the cord into aproperly grounded three-prong 110-volt AC outlet.If the cord won't reach, use a heavy-duty three-prong extension cord rated for at least 15 amps. You'll get easier starting and better fuel economy during engine warm-up. Usually, the coolant heater should be plugged in a minimum of four hours prior to starting your vehicle. 2-15