Air Control Valve A

Disconnect vacuum hose No. 16 (Accord), 29 (Civic) or 15 (Prelude) from air control valve A. Connect vacuum pump and disconnect air hose between air control valve A and frequency solenoid valve A. Connect hand vacuum pump and pressure gauge to hose. See Fig 2 .

Fig 1: View of Frequency Solenoid Valves Accord model is shown; other models are similar.
When vacuum is applied to vacuum hose side, air should flow without resistance and pressure gauge should not indicate any pressure. When vacuum is released, air should flow with resistance and pressure should build-up on gauge and release gradually. If air control valve fails either test, valve should be replaced.

Fig 2: Checking Air Control Valves Accord model is shown; other models are similar.