RAM 2500 Truck 4WD V8-5.9L VIN Z LDC (1998)
Vacuum Reservoir HVAC: Description and Operation
SYSTEM OPERATION
A vacuum reservoir is used to supply the vacuum needed to maintain proper speed control operation when engine vacuum drops, such as in
climbing a grade while driving. A one-way check valve is used in the vacuum line between the reservoir and the vacuum source. This check valve
is used to trap engine vacuum in the reservoir. On certain vehicle applications, this reservoir is shared with the heating/air-conditioning system.
The vacuum reservoir cannot be repaired and must be replaced if faulty.
Models equipped with a gasoline engine have a vacuum reservoir. The vacuum reservoir is mounted in the passenger side cowl plenum area, under
the cowl plenum cover/grille panel. The cowl plenum cover/grille panel must be removed from the vehicle to access the vacuum reservoir for
service.
Engine vacuum is stored in the vacuum reservoir. The stored vacuum is used to operate the vacuum controlled vehicle accessories during periods
of low engine vacuum such as when the vehicle is climbing a steep grade, or under other high engine load operating conditions.
The vacuum reservoir cannot be repaired and if faulty or damaged, it must be replaced.
