Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection

Manifold vacuum should be present at the air control valve through the upstream solenoid when engine coolant temperature is below 160° F, and should not be present when coolant temperature is above 160° F. If vacuum is not present when coolant temperature is below 160° F, check vacuum hoses for air leaks and proper routing, and repair as necessary. If satisfactory, replace the switch or microprocessor.