1994 GMC Suburban Owner's Manual - Page 273

Air Cleaner Refer to the Maintenance Schedule to determinewhen to replace the air filter. See "Scheduled Maintenance Services" in the Index. I NOTICE: If the air cleaneris off, a backfire can cause a damaging engine fire. And, dirt can easily get into your engine, which will damage it. Always have the air cleaner in place when you're driving. 6-27