GMC chervolet camaro 1999 Service Manual page 132

HVAC HVAC System - Manual 1-41
Noise Diagnosis
Step Action
Value(s) Yes No
DEFINITION: A constant air rush noise is typical of all heater systems when operating on HIGH blower speed. Inspect a
similar vehicle in order to determine whether the noise is typical or atypical.
1. Inspect all of the electrical connections and grounds
for proper connections.
2. Use a voltmeter in order to inspect for constant
voltage at the blower motor.
3. Sit in the vehicle.
4.
Close the doors and the windows.
1
5. Place the ignition switch in the RUN position.
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6. Leave the engine in the OFF position.
7. Set the blower speed to HIGH.
8. Set the temperature for maximum cooling.
9. Cycle through the blower speeds, modes and
temperature settings in order to find the noise.
Is the blower noise constant? Go to Step 3 Go to Step2
Listen to determine if the noise has the following
characteristics:
• Occurs only at start-up
2
• Occurs intermittently
• Occurs at cold ambients
-
-
• Occurs at low blower motor speeds
• Squeals or screeches
Does the noise have any of these characteristics?
Go to Step 5
1. Listen in order to determine if the noise has the
following characteristics:
2. Whine
3. Tick/click
3
4. Flutter
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5.
Scrape
6. Listen to determine if the noise lessens with blower
motor assembly speed reduction.
Does the noise have any of these characteristics? Go to Step 5 Go to Step 4
Listen to determine if the noise has the following
characteristics:
• The noise is constant at high blower motor speeds in
4
certain modes.
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• The noise can be eliminated at lower blower motor
speeds or other modes.
Does the noise have the above characteristics? Go to Step 12
Feel the blower motor cover at each speed in order to
5
inspect for vibration at the motor and the blower impeller.
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Is there too much vibration? Go to Step 6
1. Remove the blower motor.
2. Remove the blower impeller.
6
3. Inspect for foreign material at the orifice of the
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blower inlet.
Did you find any foreign material?
Go to Step 7 Go to Step 8
1. Repair and replace the components as necessary.
7
2. Inspect the system again.
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Was the condition corrected?
System OK