Man. Trans. Only

Warm engine to normal operating temperature and stop engine. Detach air hose at bottom of air control valve. Start engine and run at idle. Remove intake manifold vacuum line at air control valve. Air should come from bottom outlet of air control valve.
Plug disconnected vacuum line. No air should flow from bottom outlet of valve.
Remove intake manifold vacuum line from relief valve on side of air control valve. Unplug by-pass valve vacuum line and connect this line to nipple on side of relief valve from which intake manifold vacuum line was removed.
Air should flow from bottom outlet of air control valve. Disconnect vacuum line at nipple on side of air control valve. Air should not flow from bottom of valve. If valve does not respond as indicated, check vacuum lines. If okay, replace air control valve.