Servo diaphragm
Remove the air filter.
Turn off all consumers and disconnect the contact connector from the electric cooling fan.
Disconnect and plug the idle air compensator hoses, reed valves and temperature sensor.
Warm up the engine to operating temperature and connect the tachometer.
Models equipped with air conditioning
Figure 6.18. Checking the engine crankshaft speed compensator at idle speed (on models equipped with air conditioning): 1 – vacuum control tube; 2 – vacuum supply tube during testing
Disconnect vacuum tube 1 (figure 6.18).
Caution! Apply vacuum to the hose and diaphragm through the tee; the engine crankshaft speed should increase to 1200–1450 min⁻¹
. If necessary, set the specified engine crankshaft speed by turning the adjusting screw (figure 6.19).
Figure 6.19. Adjusting the diaphragm of the engine crankshaft speed compensator at idle speed (on models equipped with air conditioning)
Models equipped with power steering
Remove the air filter.
Turn off all consumers and disconnect the contact connector from the electric cooling fan.
Disconnect and plug the idle air compensator hoses, reed valves and temperature sensor.
On models equipped with air conditioning, check and adjust the servo diaphragm.
Figure 6.20. Checking the engine speed compensator diaphragm at idle speed (on models equipped with power steering): 1 – vacuum control tube; 2 – vacuum supply tube during testing
Disconnect vacuum tube 1 (figure 6.20) and through the tee apply vacuum to the hose and diaphragm.
Engine speed should increase to 800–1000 rpm for models with a manual transmission and to 1050–1250 rpm for models with an automatic transmission. If necessary, disconnect the vacuum hose and set the desired speed by turning the adjusting screw (figure 6.21).
Figure 6.21. Adjusting the diaphragm of the engine crankshaft speed compensator at idle speed (on models equipped with power steering)
Reconnect the vacuum hose and check the engine idle speed again.
Three-way valve
A three-way valve is connected between the intake manifold and the servo diaphragm.
Figure 6.22. Purpose of controlled vacuum channels on a three-way solenoid valve: A – power steering valve; B – ACVN air conditioner valve₂; C – air conditioning valve
On models equipped with air conditioning, the three-way valve shuts off the vacuum supply in accordance with a signal sent to the control unit from the air conditioning switch. On models equipped with power steering, a three-way valve cuts off the vacuum supply in accordance with a signal from the power steering switch (figure 6.22).
Figure 6.23. Extending the servo diaphragm rod with a serviceable three-way valve
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Turn on the air conditioner (the engine should idle). If the valve is working properly, the servo diaphragm rod extends (figure 6.23).
Turn off the air conditioner and turn the steering wheel all the way to the right or left. If the three-way valve and power steering switch are in good working order, the servo diaphragm rod will extend.
Power steering switch
Figure 6.24. Checking the power steering switch circuit
Disconnect the connector from the power steering switch and check the circuit through the switch as shown in the figure 6.24. With the engine idling, turn the steering wheel all the way to the right or left – the switch should be in the closed position.