Chevrolet Silverado / GMC Sierra. Service manual — part 2308

temperature?

Go to Step 10

Go to Step 8

4

1. Select the minimum blower speed.

2. Select the warmest temperature setting.

3. Feel the temperature of the inlet and outlet

hoses at the heater core.

Does the inlet heater hose feel warmer than the
outlet heater hose?

CAUTION:

Refer to Moving Parts and Hot Surfaces
Caution .

Go to Step 11

Go to Step 5

5

Test the operation of the A/C compressor
clutch.
Does the A/C compressor clutch engage?

Go to Step 7

Go to Step 6

6

Repair the A/C compressor clutch. Refer to Air
Conditioning Compressor Malfunction for
the automatic system or to Air Conditioning
Compressor Malfunction for the manual
system.
Is the repair complete?

Go to Step 14

-

7

Perform the A/C system performance test. Refer
to Air Conditioning (A/C) System
Performance Test (Diesel Engine) or

Air

Conditioning (A/C) System Performance
Test (Gas Engine w/ Electric Cooling Fan)

or Air Conditioning (A/C) System
Performance Test (Gas Engine w/Engine
Driven Fan).
Is the A/C system operating within the
specifications?

Go to Step 9

Go to Step 12

8

Repair the low engine temperature concern.
Refer to Engine Fails To Reach Normal
Operating Temperature .
Is the repair complete?

Go to Step 14

-

9

Inspect for correct operation of the recirculation
door.
Is the recirculation door operating correctly?

Go to Step 14

Go to Step 13

2008 Chevrolet Silverado 1500

2008 HVAC Heating, Ventilation, and Air Conditioning - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

NOISE DIAGNOSIS - BLOWER MOTOR

10

Repair the air delivery concern. Refer to
Diagnostic Starting Point - Heating,
Ventilation and Air Conditioning.
Is the repair complete?

Go to Step 14

-

11

Repair the heating concern. Refer to Heating
Performance Diagnostic.
Is the repair complete?

Go to Step 14

-

12

Repair the A/C performance concern. Refer to
Air Conditioning (A/C) System
Performance Test (Diesel Engine) or Air
Conditioning (A/C) System Performance
Test (Gas Engine w/ Electric Cooling Fan)
or Air Conditioning (A/C) System
Performance Test (Gas Engine w/Engine
Driven Fan).
Is the repair complete?

Go to Step 14

-

13

Repair the recirculation door concern. Refer to
Diagnostic Starting Point - Heating,
Ventilation and Air Conditioning.
Is the repair complete?

Go to Step 14

-

14

Operate the system in order to verify the repair.
Did you find and correct the condition?

System OK

Go to Step 2

Step

Action

Yes

No

1

Were you sent here from Symptoms or another
diagnostic table?

Go to Step 2

Go to Symptoms
- HVAC
Systems -
Manual
or
Go to Symptoms
- HVAC
Systems -
Automatic

2

Inspect the air inlet grille for debris.
Is debris present?

Go to Step 8

Go to Step 3

1. Sit inside the vehicle.

2008 Chevrolet Silverado 1500

2008 HVAC Heating, Ventilation, and Air Conditioning - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

3

2. Close the vehicle doors and windows.

3. Turn ON the ignition, with the engine

OFF.

4. Cycle the blower motor through all of the

speeds and modes in order to determine
where and when the noise occurs.

Is a noise evident during the blower operation?

Go to Step 4

Go to Step 11

4

Inspect for excessive vibration at each blower
motor speed by feeling the blower case.
Is excess vibration present?

Go to Step 6

Go to Step 5

5

Listen to the blower motor at each speed.
Is the blower motor making a squeaking or
chirping noise?

Go to Step 9

Go to Step 11

6

1. Remove the blower motor. Refer to

Blower Motor Replacement.

2. Inspect the blower motor impeller for

deposits of foreign material.

3. Inspect the blower motor for deposits of

foreign material.

Did you find any foreign material on the blower
motor or blower motor impeller?

Go to Step 8

Go to Step 7

7

Inspect the blower motor for the following
conditions:

Cracked blades

A loose impeller retainer

Improper impeller alignment

Did you find any of these conditions?

Go to Step 9

Go to Step 10

8

Remove the foreign material.
Is the action complete?

Go to Step 10

-

9

Replace the blower motor. Refer to Blower
Motor Replacement.
Is the repair complete?

Go to Step 11

-

2008 Chevrolet Silverado 1500

2008 HVAC Heating, Ventilation, and Air Conditioning - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

NOISE DIAGNOSIS - AIR CONDITIONING (A/C) SYSTEM

10

Install the blower motor. Refer to Blower
Motor Replacement.
Is the action complete?

Go to Step 11

-

11

Operate the system in order to verify the repair.
Did you find and correct the condition?

System OK

Go to Step 2

Step

Action

Yes

No

1

Were you sent here from Symptoms or another
diagnostic table?

Go to Step 2

Go to Symptoms
- HVAC
Systems -
Manual
or
Go to Symptoms
- HVAC
Systems -
Automatic

2

1. A/C system noises can be generally

categorized into 3 areas:

Screeching, squealing, chirping noises

Moaning noises

Vibration/rattle noises

2. Start the engine.

3. Ensure that the A/C is ON.

Is a screeching, squealing noise heard when the
A/C is engaged?

Go to Step 3

Go to Step 9

3

With the engine OFF, inspect the drive belt for
excessive wear. Refer to Drive Belt Falls Off
and Excessive Wear Diagnosis .
Is the drive belt excessively worn?

Go to Step 18

Go to Step 4

4

Inspect the drive belt tension. Refer to Drive
Belt Tensioner Diagnosis .
Is the drive belt tension correct?

Go to Step 19

Go to Step 5

5

Inspect the drive belt for excessive oil coverage.
Is the drive belt covered with oil?

Go to Step 17

Go to Step 6

2008 Chevrolet Silverado 1500

2008 HVAC Heating, Ventilation, and Air Conditioning - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado