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5.5.3.2.
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 vacuum tester to the
port (fig.9) 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 noted.
5.5.4.
TESTING VACUUM OpERATED HEATER TApS
5.5.4.1.
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 turn the heater tap 'on'.
5.5.4.2.
To test these remove the supply line from the tap vacuum module and connect the vacuum tester (fig.10). 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.
5.5.5.
TESTING VACUUM OpERATED REMOTE CENTRAL LOCKING SYSTEMS
5.5.5.1.
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.
5.5.5.2.
In either system, the 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 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
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.
5.5.6.
TESTING AUTOMATIC TRANSMISSION VACUUM OpERATED MODULATOR VALVES
5.5.6.1.
Automatic transmissions are normally equipped with a vacuum operated modulator valve in order for the automatic transmission to detect
engine loads and adjust shift points to suit.
5.5.6.2.
The 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 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.
5.5.6.3.
to check modulator pressure readings attach a pressure gauge to the appropriate port on the transmission. remove the vacuum supply
line from the modulator and attach the vacuum tester (fig.12). Start and run the engine and apply vacuum pressures. Monitor readings
and confirm that these are in conformance with manufacturer's specifications.
fig.7
fig.9
fig.11
© Jack sealey limited
fig.8
fig.10
fig.12
Original Language Version
VS4022.V2
Issue 1 17/01/18
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