Vacuum Solenoid Valve HVAC: Testing and Inspection

Fig. 19 Vacuum switching valve test.:

1. Disconnect electrical connectors and vacuum hoses from valve.
2. Check for vacuum circuit continuity between by connecting valve to a suitable 12 volt source as shown, Fig. 19.
3. Blow into pipe F and ensure air comes from pipe E.
4. Disconnect battery cables, then blow into pipe F and check that air comes from filter G, not pipe E.
5. If air is not expelled as described, replace valve.
6. Using a suitable ohmmeter, check for continuity between each terminal and valve body. If continuity is found, a short circuit is indicated and valve should be replaced.
7. Using a suitable ohmmeter, check the resistance between the two valve terminals. Resistance should be 38-44 ohms. If resistance is not as specified, replace valve.