Vacuum Amplifier: Testing and Inspection

1. Using a 'T' fitting, connect a vacuum gauge to the vacuum hose that extends from the vacuum amplifier to the port on the throttle housing.
2. With the engine at idle, the vacuum should be 5 - 8 mm Hg (0.2 - 0.3 in Hg).
3. If vacuum is not within specifications, check the vacuum port in the throttle housing. Clean the vacuum port if it is clogged.
4. Once it is determined that adequate vacuum is reaching the vacuum amplifier, connect the vacuum gauge between the vacuum amplifier and the temperature valve with a 'T' fitting. At idle vacuum should be 50 - 90 mm Hg (2 - 4 in Hg).
5. If vacuum is not within specification, the vacuum amplifier is faulty and should be replaced.

Fig. 1 Vacuum amplifier connections:

1. Start engine and allow to idle.
2. Connect a vacuum gauge in line between vacuum amplifier and throttle assembly, Fig. 1. Gauge should read between .2 to .3 inches of Hg, if not, check vacuum lines for blockage and/or adjust throttle plate position.
3. Connect vacuum gauge in line between amplifier and temperature valve. Gauge should read between 2 to 4 inches of Hg, if not, replace vacuum amplifier.