1998 GMC Savana Van Owner's Manual - Page 118

Your electric outside rearview mirrors can be defrosted by pressing the switch next to the heater controls. (See "Comfort Controls" in the Index). Convex Outside Mirror Your passenger's side mirror may be convex. A convex mirror's surface is curved so you can see more from the driver's seat. A convex mirror can make things (like other vehicles) look farther away than they really are. If you cut too sharply into the right lane, you could hit a vehicle on your right. Check your inside mirror or glance over your shoulder before changing lanes. 2-46