Air Injection Control Valve: Testing and Inspection

1. Disconnect the two output hoses from air switch valve, noting which was connected to "upstream" port and which was connected to "downstream" port.
2. Start engine and disconnect vacuum hose from small valve nipple.

NOTE: There should be vacuum at vacuum hose when engine coolant temperature is below 160° F, and no vacuum when temperature is above 160° F. If coolant is below 160° F and there is no vacuum present at hose, check hose for air leaks. If there are no leaks, replace the CT0 valve.

3. Air pressure should be present at air switch valve port that connects to "downstream" hose. A small amount of air pressure should be present at "upstream" port of air control valve.
4. Apply at least 10 inches Hg of vacuum to small nipple on air switch valve. Air pressure should be present at "upstream" port, with very little air pressure at "downstream" port.