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6.
ADDITIONAL VACUUM SYSTEMS
6.1.
Testing
One-Way
Valves
6.1.1.
Many vacuum operated circuits use in-line one-way
valves
to
apply
vacuum in one direction
only.
6.1.2. To test the function
of
the
valve
remove it from
the
circuit. Attach the VS402.V2 vacuum tester
(fig.7) and operate
pump
to
apply vacuum.
In one direction
the
valve
should
hold
vacuum and in
the opposite
direction it
should
not.
6.2.
Testing Electrically Operated Vacuum Solenoids
6.2.1.
Electrically
operated vacuum solenoids
are
commonly
used
in
control
circuits for
air conditioning/ventilation
systems,
emission
control systems,
idle step up
systems etc. and
testing
the function of these when
using
the VS402.V2 is extremely
simple.
6.2.2. Locate
the
solenoid to be tested and remove
the
line
that goes
to
the
component being
tested.
Connect the VS402.V2
to
the
solenoid port (fig.8)
and start
the
engine.
With
the system
turned off
there should·be
a zero
gauge reading. Now turn
the system to
the
'on' position and
a gauge
reading equal
to the
manifold
vacuum
should
be observed,
if no reading
exists remove
the
vacuum
supply
line and
test for manifold
vacuum
at
this
point. If the vacuum
does
exist
this indicates
that
the
solenoid
is faulty or
it
is
not
receiving a 'switch on'
voltage (use a multimeter to test this).
If no
vacuum exists trace
the
supply
line
back to the vacuum source checking
for kinks
and
breaks.
6.3.
Testing Thermal Vacuum
Switches
6.3.1. There are many vacuum controlled circuits
that must
only operate when
the
engine
reaches
nonnal
operating
temperature.
This
is done using thennal
switches
that remain
in an 'off position
until
a given temperature is
reached.
6.3.2.
To test
this type of switch, remove the vacuum supply line coming from the manifold to
the
switch and
test
for
manifold
vacuum. If
this vacuum is correct refit
the supply
line
to the thermal
switch and remove the opposing
line
from
the switch.
Attach
the VS402.V2 vacuum
tester
to the port
(fig.9)
and start the
engine.
With a cold engine
no
reading
should
be noted. When
the
engine
reaches
nonnal operating temperature a
manifold
vacuum reading
should
be
noted.
6.4.
Testing
Vacuum Operated Heater Taps
6.4.1. Climate control ventilation systems are becoming very common
on
newer vehicles and most of
the
systems use vacuum operated taps to control the heating
modes.
On
the
majority of makes and
models,
the system uses vacuum to
tum
the heater tap
'on'.
6.4.2.
To test
these remove the supply line
from the
tap
vacuum
module
and
connect the VS402.V2 vacuum
tester
(fig.10).
With the engine at
nonnal
operating
temperature
locate and
feel
the
heater
return
hose. With the
heater
tap in the 'otr
position,
this hose
should
be
cold. Now
operate
the
vacuum
pump to
open
the tap.The
gauge reading
must hold.
If
the
tap
is
in
working
order.
the retum hose will begin to heat. If the hose
does not begin
to heat,
this indicates
that
the tap
is
faulty.
6.5.
Testing Vacuum Operated Remote Central
Locking
Systems
6.5.1. Some makes and models use vacuum operated bellows mounted in each door to centrally lock and unlock the vehicles doors. These systems
use either
manifold vacuum stored in a
reservoir
for use
when the engine
is not
running or an electrically driven vacuum pump which operates when the doors
are
locked
or unlocked.
6.5.2.
In either
system,
the
VS402.V2 vacuum
tester
is ideal for testing
each individual
door
bellows.
To
do
this.
removA
the door trims
as required. Remove
the
vacuum
supply lines
from the bellows
and
attach
the VS402.V2
vacuum tester
(fig.11
) and operate to apply vacuum
to
the
bellows. Wait
for 30
seconds, no
drop
on
the gauge should be noted. If the bellows are found to
be in
order
attach the
vacuum
supply
line
to the
VS402.V2
vacuum
tester and operate
system
to test
for vacuum
supply.
If
the vacuum supply does not exist or is low trace
back
down the lines to the vacuum
supply
looking for kinks, restrictions
or cracked
lines.
Repair
as
required and retest.
6.6.
Testing
Automatic
Transmission Vacuum Operated
Modulator Valves
6.6.1. Automatic transmissions are nonnally equipped with a vacuum operated
modulator
valve in order
for
the automatic transmission to detect engine loads and
adjust
shift points to
suit.
·
6.6.2.
The
VS402.V2
vacuum
tester can be
used
to test both that the
modulation
valve
diaphragm
is serviceable and also to simulate varying
engine
loads
so
modulator
pressure readings can be
recorded.
To
test
the
modulator
valve diaphragm remove
the
vacuum
supply line
from the valve and attach
the
VS402.V2
vacuum
tester. Operate the
vacuum pump until approximately
15inHg
is
achieved
and
monitor the
gauge
reading for
approximately 30 seconds.
No
vacuum drop should
be
noted.
6.6.3.
To
ctleck modulator pressure
readings
attach a
pressure gauge to the appropriate port on the transmission. RerllOYe the
vaaMTI
supply line
from the
modulator and attach
the
VS402.V2 vacuum
tester
(fig.12). Start and run the engine and
apply vacuum
pressures.
Monitor readings and confinn that
these
are in conformance with manufacturer
specifications.
(
C>
Jack Sealey Umited
l
To
Manifold
)
Vawum
Original
Language
Version
(
VS402.
V2
I
Issue: 1 • 22105112 )
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