1998 Chevrolet Express Van Owner's Manual - Page 104

A CAUTAN: I CAUTION: (Continued) Thrn the fan on your heating cooling or system to its highest speed with the setting on VENT, HEAT, BLEND or DEE Additionally, on vehicles withheatingair conditioning systems,NORM A/C or BI-LEVEL A/C can beused. That will force outside air into your vehicle. See "Comfort Controls" in the Index. If you have air outlets onor under the '. instrument panel, open them all the way. See "Engine Exhaust" in the Index. It can be dangerous to drive with the rear swing-out windowsor rear door(s) open because carbon monoxide (CO) gas can come into your vehicle. You can't see or smell CO. It can cause unconsciousness and even death. If you must drive with the rear swing-out windows or rear door(s) open ifor electrical wiring or other cable connections must pass through the seal between the body and the rear swing-out windows or reardoor(s): Make sure allwindows are shut. CAUTION: (Continued) Horn Press the horn symbol in the middle of the steering wheel to sound the horn.