Air Control Valve

Operate engine to normal operating temperature. Stop engine and install tachometer. On turbo models equipped with Anti-Lock Brake Systems (ABS), disconnect and plug air hose and vacuum hose of air by-pass valve from the turbo.
CAUTION: On turbo models with Anti-Lock Brake Systems (ABS), ensure air hose and vacuum hose of air by-pass valve are disconnected and plugged prior to removing air silencer-to-air control valve hoses.
On all models, disconnect air silencer-to-air control valve hose at air control valve. Place finger over air control valve outlet. Start engine and increase engine speed to 3750 RPM on turbo models or 1500-2500 RPM on non-turbo models. Note that air begins to flow at specified RPM.
Operate engine at idle. On turbo models, disconnect relief valve solenoid Blue connector. See Fig 1 . On non-turbo models, disconnect relief valve solenoid-to-air control valve hose. See Fig 1 .

Fig 1: Disconnecting Relief Valve Or Switching Solenoid Valve
Courtesy of MAZDA MOTORS CORP.
Check that air flows from air control valve outlet above 1200 RPM on turbo models or at idle on non-turbo models. Reconnect vacuum hose or Blue connector.
Remove intake manifold-to-check valve hose. Disconnect hose at check valve on turbo models or intake manifold on non-turbo models. Place finger over opening.
On turbo models, disconnect hose at air control valve at air control valve. See Fig 2 . On non-turbo models, disconnect hose at switching solenoid valve. See Fig 1 .

Fig 2: Disconnecting Switching Solenoid Valve (Turbo)
Courtesy of MAZDA MOTORS CORP.
With engine at idle, note that air flows from intake manifold fitting (non-turbo) or check valve (turbo). Replace air control valve if necessary. Reconnect all hoses.