V
Vacuum Sources:
VACUUM - The lack of air or air pressure. There are three types of vacuums important to engine and component function: manifold, ported and venturi. The strength of these vacuums is dependent on throttle opening, engine speed and load.
VACUUM CHECK VALVE (VCV) - Used to retain vacuum signal in a line after vacuum source is gone.
VACUUM CONTROL CHECK VALVE - VCKV
VACUUM CONTROL TEMPERATURE SENSING VALVE (VCTS) - A valve that connects manifold vacuum to the distributor advance mechanism under hot idle conditions.
VACUUM CONTROL VALVE (VCV) - Controls vacuum to other emission devices during engine warm-up. The 2-port types simply open when engine coolant reaches their pre-determined calibration temperatures. The 4-port types open likewise, since they are nothing more than two, 2-port types in one housing. The 3-port types switch the vacuum source to the center port from the top or the bottom ports. Electrical switches can be either open or closed until the VCV is hilly cycled. Most VCV's respond to a sensing bulb immersed in engine coolant by utilizing a wax
pellet principle. The only exception is the 9F454 which operates on a bimetal principle. Vacuum is usually sourced as illustrated.
VACUUM CONTROLLED SWITCH - VCS
VACUUM CONTROLLED SWITCH-COLD TEMPERATURE - VCS-CT
VACUUM CONTROLLED SWITCH-DECEL IDLE - VCS-DI
VACUUM DELAY VALVE (VDV) - See "delay valve"
VACUUM DIFFERENTIAL VALVE (VDV) - A valve used in the Thermactor system with catalyst to cut off vacuum to the air bypass valve during deceleration.
VACUUM OPERATED THROTTLE
MODULATOR - VOTM
VACUUM REGULATOR - Provides constant vacuum output when vehicle is at idle from manifold. Switches to engine vacuum off idle.
Vacuum Regulator/Solenoid:
VACUUM REGULATOR/SOLENOID (VR/S)
- Used to control vacuum and idle air bleed to the 6149 feedback carburetor on 2.3L HSC engines.
2 Port Vacuum Regulator Valve:
VACUUM REGULATOR VAWE (VRV) 2-port
- Vacuum regulator which provides a constant output signal when the input level is greater than a preset level. At a lower input vacuum the output equals the input.
VACUUM REGULATOR VALVE (VRV) 3- & 4-port - 3-port and 4-port valves are used to control the vacuum advance to the distributor.
VACUUM RESERVOIR (VRESER) - Stores vacuum and provides "muscle vacuum." Prevents rapid fluctuations and sudden drops in a vacuum signal, such as seen during acceleration.
Vacuum Restrictor:
VACUUM RESTRICTOR (VREST) - Used to control the flow rate and/or timing inactions to different emission control components.
VACUUM RETARD DELAY VALVE (VRDV) - A valve which delays a decrease in vacuum at the distributor vacuum advance unit when the source vacuum decreases.
VACUUM VENT VALVE (VVV) - Controls the induction of fresh air into a vacuum system to prevent chemical decay of the vacuum diaphragm that can occur on contact with fuel. The 12A226 (natural cap) is a combined vent and delay valve. Although this valve was intended for use in a specific system with an air cleaner mounting, it may be used in any other vacuum system and mounted elsewhere. The valve should be mounted, as shown, with ports pointing downward for fuel drainback. The vacuum source must be connected to the cap port and the system or device operated, to the body port, as shown.
Vane Air Temperature:
VANE AIR TEMPERATURE (VAT) - A sensor located in the vane airflow meter which senses the temperature of the air flowing into the engine. Changes of temperature result in changes in a resistive element in the sensor.
Vane Airflow Meter:
VANE AIRFLOW METER (VAF) - A sensor with a movable vane connected to a potentiometer calibrated to measure the amount of air flowing through the sensor. The output signal is relayed to the ECA which then translates the information into the amount of air flowing into the engine.
VANE METER (VM) - See "Vane Airflow Meter."
VANE TYPE DIFFUSER - Designed so the leading edge will be in line with the direction of the air flow from the impeller. The vane curvature will force air to flow or be slowed down as required for the specific engine application. This design allows for a high peak efficiency.
VAPOR-RECOVERY SYSTEM - See "Evaporative Emission Controls."
VEHICLE BATTERY VOLTAGE - VBAT
Vehicle Emission Control Information Decal:
VEHICLE EMISSION CONTROL INFORMATION DECAL (VECI) - Critical specifications for servicing emission systems. Decal located in engine compartment.
VEHICLE SPEED SWITCH (Courier) - Attached to speedometer to help control air/fuel mixture at cruising speed.
VENT VALVE VACUUM DELAY Delays vacuum to the distributor through a sintered disk.
VENTURI VACUUM AMPLIFIER (VVA) - Used with some EGR systems so that carburetor venturi vacuum can control EGR valve operation. Venturi vacuum is desirable because it is proportional to the airflow through the carburetor.