Thermal Vacuum Switch (TVS)

1. Cool air cleaner to below the TVS calibration point of 40 to 50° F.
2. Disconnect vacuum lines from TVS and connect a vacuum gauge to one port and a vacuum pump to the other port.
3. Apply vacuum to TVS. There should be no vacuum reading indicated on the gauge when TVS temperature is below its calibration point. If there is, replace the TVS.
4. Start engine and allow temperature of TVS to reach 40 to 50° F. Vacuum should be indicated through TVS. If not, replace TVS.