GMC chervolet camaro 1999 Service Manual page 130

HVAC
HVAC System - Manual 1-39
Improper Air Delivery Diagnosis
Step
Action
Value(s) Yes
No
1. Perform the preliminary inspection.
2. Set the mode selector valve in the OFF position.
3. Disconnect the vacuum line at the check valve.
1
4.
Use a hand vacuum pump in order to apply vacuum
-
to the vacuum line that leads to the mode
selector valve.
Does the vacuum hold?
Go to Step 3 Go to Step2
1. Inspect the black vacuum line that leads to the mode
selector valve.
2
2. Replace the mode selector valve if the line is
-
-
connected and working properly.
Is the replacement complete? System OK
1. Apply vacuum to the vacuum line that leads to the
3
mode selector valve.
-
2. Inspect each setting (MAX A/C to DEFROST).
Does vacuum hold in every setting? Go to Step 4 Go to Step 8
1. Disconnect the vacuum line multi-connector under the
right side sound insulator.
2. Tum the ignition switch to the RUN position (engine
not running).
4
3. Select the HIGH blower motor assembly speed.
-
4. Apply vacuum to each vacuum line individually
(except for the black and orange lines).
5.
Inspect the lines for air flow at the proper outlets.
Refer to the Diagnostic Aid Chart.
Does air flow at the correct outlets?
Go to Step 6
Go to Step 5
Repair or replace the actuator linkage and/or air
5
valve (door). -
-
Is the repair complete
System OK
6
Apply vacuum to the orange vacuum line.
-
Does the blower motor air flow noise increase?
System OK
Go to Step 7
Repair or replace the air inlet vacuum actuator linkage
7
and/or air inlet valve.
-
-
Is the repair complete? System OK
1. Disconnect the vacuum line multi-connector at the
mode selector valve.
8
2. Apply vacuum to each line at the multi-connector that
-
is controlled by the mode selector valve at a setting
where vacuum did not hold.
Is a vacuum leak present at one or more lines?
Go to Step 9
Go to Step 10
Repair or replace the vacuum line and/or the vacuum
9
actuator.
-
-
Is the repair complete?
System OK
10
Replace the mode selector valve.
-
-
Is the replacement complete? System OK