1994 Chevrolet Blazer Owner's Manual - Page 250

Air Cleaner To remove the round air cleaner filter for the 4.3L (VIN Z) engine, turn the wing nuts to the left. Remove thecover and change the filter. Care should be taken during reassembly to ensure that the cover is on straight and the wingnuts are properly tightened. I" a To remove the square air cleaner filter for the 4.3L (VIN W) high performance engine, loosen both wingnuts (one on the duct and one on the cover). Lift the air cleaner assembly up from the vehicle. Open both clamps and lift off cover to change the filter. While reassembling the air cleaner assembly, ensure that the air cleaner cover tabs are fully inserted into the slots in the air cleaner housing, the two wingscrews are secured, and the PCV tube is air properly seated in the left hand valve cover. Refer to the Maintenance Schedule to determine when to replace the air filter. See "Scheduled Maintenance Services'' in the Index. 6- 14