Vacuum Diaphragm, Replace

Fig.18 Removing Vacuum Diaphragm:

1. Remove air cleaner housing.
2. On 1970-73 vehicles, bend down lock tab, Fig. 18, and lift forward edge of diaphragm to clear lock tab, then slide forward to disengage rear lock tab. Slide diaphragm to the right to unlock operating rod from heat control valve.

Fig.19 Removing Vacuum Diaphragm:

3. On 1974-82 vehicles, disconnect vacuum hose from the diaphragm, drill through the welded tab, Fig. 19, and tip diaphragm forward to disengage lock, then rotate diaphragm counterclockwise. When diaphragm is free from snorkel, slide the complete assembly to one side and disengage operating rod from heat control door.
4. With diaphragm removed, check door for freedom of travel. The door should fall freely when released from the full up position. If it does not, inspect door to snorkel side walls and hinge pin for interference. Remove any foreign matter with compressed air.
5. Reverse procedure to install. On 1974-82 vehicles, pop rivet tab in place. Apply 9 inches of vacuum to diaphragm hose nipple and check that control door operates freely.

NOTE: Manually operating the heat control door could result in damage, leading to malfunctioning of the system.