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5.7.
TESTING ELECTRICALLY OPERATED VACUUM SOLENOIDS
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 VS403.V3 is extremely simple. Locate the
solenoid to be tested and remove the line that goes to the component being tested. Connect the VS403.V3 to the solenoid port (fig.10)
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 or breaks.
TESTING THERMAL VACUUM SWITCHES
5.8.
There are many vacuum controlled circuits that must only operate when the engine reaches normal operating temperature. This is
done using thermal switches that remain in an 'off' position until a given temperature is reached. 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 VS403.V3 vacuum tester to the port
(fig.11) and start the engine. With a cold engine no reading should be noted. When the engine reaches normal operating temperature
a manifold vacuum reading should be seen.
5.9.
TESTING VACUUM OPERATED HEATER TAPS
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 turn the heater tap
'on'. To test these remove the supply line from the tap vacuum module and connect the VS403.V3 vacuum tester (fig.12). With the
engine at normal operating temperature locate and feel the heater return hose. With the heater tap in the 'off' 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
return hose will begin to heat. If the hose does not begin to heat this indicates that the tap is faulty.
5.10.
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. In either system, the VS403.V3 vacuum tester is ideal for
testing each individual door bellows. To do this,remove the door trims as required. Remove the vacuum supply lines from the bellows
and attach the VS403.V3 vacuum tester (fig.13) 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 VS403.V3 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.
fig.13
© Jack Sealey Limited
fig.11
TESTING VACUUM OPERATED REMOTE CENTRAL LOCKING SYSTEMS
Original Language Version
fig.12
VS403.V3
Issue: 4 (H,F) 17/05/23
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