Vacuum actuator DAEWOO LACETTI 2004 Service Repair Manual

ENGINE CONTROLS 1F – 79
DAEWOO V–121 BL4
IDLE AIR CONTROL SYSTEM CHECK (1.4L/1.6L DOHC)
Circuit Description
The aim of the MTIA (Main Throttle Idle Actuator) is to con-
trol the idle speed with the throttle body itself. The throttle
is motorized for low opening angle (0°C, 19°C). The char-
acteristics of the airflow are not the same for low and high
opening angles. As a matter of fact, the gradient of the
mass air flow function of TPS is lower for small angles that
permits to be more precise during the idle speed control.
Out of idle speed the throttle is actuated mechanically by
a classical bowdencable.
The main throttle idle actuator (MTIA) provides a voltagesignal that changes in relation to the throttle plate angle.
The signal voltage will vary from about nearly 5.0 V at idles
to about 0.2V to 0.4 V at wide–open throttle. The TPS is
one of the most important inputs used by the ECM for fuel
control and other functions such as idle, wide open
throttle, deceleration enleanment, and acceleration en-
richment.
Diagnostic Aids
If the idle is too high, stop the engine. Fully extend the main
throttle idle actuator (MTIA) with a IAC driver. Start the en-
gine. If the idle speed is above 800 rpm, locate and repair
the vacuum leak. Also, check for a binding throttle plate or
throttle linkage or an incorrect base idle setting.

7A – 12IHEATING AND VENTILATION SYSTEM
DAEWOO V–121 BL4
StepActionValue(s)YesNo
1Verify the customer’s complaint.
Are the customer’s concerns verified?Go to Step 2System OK
2S Examine the affected door in the unit for proper
attachment to the vacuum actuator.
S Check the actuator connection to the door.
S Check that the vacuum hose is properly con-
nected.
Is everything connected properly?–Go to Step 4Go to Step 3
3Repair as necessary.
Is the repair complete?–System OK–
41. Disconnect the actuator at the door.
2. Check the range of the door travel and the ef-
fort required to move it.
Does the door move freely through its entire range
of travel so that it can close at both ends of the
range?–Go to Step 5Go to Step 3
5Check the travel of the actuator by turning the con-
trol knob with the engine running.
Is the actuator travel OK?–Go to Step 6Go to Step 7
61. Reinstall the actuator.
2. Recheck the system using the ”Control Set-
tings/Correct Results” tests in this procedure.
Does the system perform properly?–System OKGo to Step 9
71. Check the vacuum hose at the control.
2. Check for a broken control.
Is there a problem with the vacuum hose or the con-
trol?–Go to Step 8Go to Step 9
8Repair the vacuum hose or the control as necessary.
Is the repair complete?–System OKGo to Step 9
9Recheck the system using the ”Control Settings/
Correct Results” tests in this procedure.
Is the repair complete?–System OKGo to Step 10
10Check for airflow from the defroster or the vent out-
lets.
Is there high airflow from the defroster or the vent
outlets?–Go to Step 11Go to Step 12
11Adjust the heater door at the floor and the vent door
to get the proper airflow.
Is the repair complete?–System OK–
12Switch the mode knob to defrost.
Is the defroster airflow OK?–Go to Step 13Go to Step 14
131. Remove the heater outlet.
2. Check the heater outlet for obstructions.
3. Remove any obstructions in the heater outlet.
Is the repair complete?–System OK–
14Check the blower speeds for change in the airflow.
Does the blower speed increase as the control is
turned from 1 to 4?–Go to Step 15Go to ”Blower
Electrical
(Manual and
Non–A/C)”

HEATING AND VENTILATION SYSTEM 7A – 13
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
151. Check for obstructions in the system at the
blower inlet and check the air filter if the vehicle
is so equipped.
2. Remove any obstructions at the blower inlet
and replace the filter if it is clogged.
Is the repair complete?–System OKGo to Step 16
161. Set the blower on 4.
2. Rotate the temperature control from full hot to
full cold.
3. Listen for an airflow change.
Does the airflow change?–Go to Step 17Go to Step 18
171. Check the temperature door, the cable, the
linkage, and the control.
2. Adjust the temperature control to full hot.
Is the repair complete?–System OK–
181. Check the system for any obstruction between
the blower and the system outlets.
2. Remove any obstruction between the blower
and the system outlets.
Is the repair complete?–System OK–
TOO MUCH HEAT
StepActionValue(s)YesNo
1Verify the customer’s complaint.
Are the customer’s concerns verified?–Go to Step 2System OK
2Is there too much heat when the mode switch is in
the floor position?–Go to Step 3Go to Step 9
3Is there objectionable defroster bleed?–Go to Step 4Go to Step 5
41. Check the door travel, the cable, the vacuum
actuators, and the linkage for the heater and
the defroster.
2. Adjust or repair, as required.
Is the repair complete?–System OK–
51. In vehicles equipped with A/C, set the A/C
switch OFF.
2. In all vehicles, set the blower speed to maxi-
mum.
3. Set the temperature to full hot.
4. Turn the ignition switch ON.
5. Check for airflow from the floor outlets.
6. Check the floor outlet attachment.
Is the airflow high?–Go to Step 6Go to Step 8
6Check for a change in the airflow at different blower
speeds.
Does the airflow change as the setting for the blow-
er–speed switch is scanned?–Go to Step 7 Go to ”Blower
Electrical
(Manual and
Non–A/C)”