toyota Workshop Repair Guides

Toyota Workshop Service and Repair Manuals

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Thermal Vacuum Valve - EVAP: Description and Operation

PURPOSE

The thermal vacuum valve (TVV) prevents charcoal canister purging below 129° F (54° C). Low temperature purging is delayed to prevent the
possible leaning of the cold fuel mixture.

LOCATION

The valve is threaded into the water jacket near the distributor.

CONSTRUCTION

The valve consists of a bimetallic spring and a sealing plate. 

OPERATION

During low water temperature, the bimetallic spring contracts, closing the vacuum passage through the TVV. When the temperature rises above
129° F (54° C), the spring expands opening the vacuum passage, allowing purge vacuum to reach the canister.

 

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