C 10 1/2 Ton Pickup 2WD V8-305 5.0L VIN H 4-bbl (1982)
Vacuum Check Valve: Description and Operation
Located in the vacuum line from the carburetor to the EFE thermal vacuum switch--the EFE-CV holds the highest vacuum reached, enabling the
EFE heat valve to remain closed until the TVS switches modes.
It also prevents the heat valve from rattling during severe low vacuum conditions (heavy acceleration).
