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Chevrolet Silverado / GMC Sierra. Manual - part 2302
Fig. 3: A/C System Pressure Zone Classification - Gas Engine With Engine Driven
Cooling Fan
Courtesy of GENERAL MOTORS CORP.
A/C Performance Table - Gas Engine With Engine Driven Cooling Fan
Ambient Air
Temperature
Relative
Humidity
Service Port Pressure
Maximum
Left Center
Discharge
Air
Temperature
Low Side
High Side
13-16°C (55-
65°F)
0-100%
150-246 kPa (25-36
psi)
730-1190 kPa (106-
173 psi)
12°C (54°F)
19-24°C (66-
75°F)
Below 40%
150-280 kPa (22-41
psi)
900-1390 kPa (131-
202 psi)
14°C (57°F)
Greater than
40%
179-137 kPa (26-46
psi)
990-1500 kPa (144-
218 psi)
16°C (61°F)
2008 Chevrolet Silverado 1500
2008 HVAC Heating, Ventilation, and Air Conditioning - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
AIR CONDITIONING (A/C) DIAGNOSTICS - PRESSURE ZONE A
25-29°C (76-
85°F)
Below 35%
218-328 kPa (32-48
psi)
1240-1640 kPa (180-
238 psi)
17°C (63°F)
35-60%
236-342 kPa (34-50
psi)
1290-1680 kPa (187-
244 psi)
18°C (64°F)
Above 60%
250-365 kPa (36-53
psi)
1340-1760 kPa (194-
255 psi)
20°C (68°F)
30-35°C (86-
95°F)
Below 30%
266-386 kPa (39-56
psi)
1500-1940 kPa (218-
282 psi)
21°C (70°F)
30-50%
280-397 kPa (41-58
psi)
1540-1990 kPa (224-
289 psi)
22°C (72°F)
Above 50%
330-430 kPa (44-62
psi)
1600-2070 kPa (232-
300 psi)
24°C (75°F)
36-41°C (96-
105°F)
Below 20%
328-439 kPa (48-64
psi)
1810-2240 kPa (263-
325 psi)
25°C (77°F)
20-40%
337-457 kPa (49-66
psi)
1840-2290 kPa (267-
332 psi)
26°C (79°F)
Above 40%
355-474 kPa (52-69
psi)
1890-2340 kPa (274-
340 psi)
27°C (81°F)
42-46°C (106-
115°F)
Below 20%
391-491 kPa (57-71
psi)
2130-2500 kPa (309-
363 psi)
29°C (84°F)
Above 20%
397-508 kPa (58-74
psi)
2160-2550 kPa (313-
370 psi)
30°C (86°F)
47-49°C (116-
120°F)
Below 30%
451-552 kPa (65-80
psi)
2420-2790 kPa (351-
405 psi)
33°C (92°F)
Step
Action
Value
Yes
No
DEFINITION: The high and low side pressures may be normal or slightly less than normal.
Air Delivery Concern
Slight Refrigerant Under Charge
Refrigerant Contamination
Were you sent here from the A/C System
Performance Test?
Go to Air
Conditioning
(A/C) System
Performance
Test (Diesel
2008 Chevrolet Silverado 1500
2008 HVAC Heating, Ventilation, and Air Conditioning - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
1
-
Go to Step 2
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)
2
Refer to the panel air outlet temperatures
recorded during the A/C system
performance test.
Does the discharge air temperature
between the right and left center panel
outlets vary by more than 1-2°C (2-3°F)?
-
Go to Step 7 Go to Step 3
3
Did the customer mention that the A/C
system output temperatures are good at
first, but then turn warm during extended
drives?
-
Go to Step 4 Go to Step 5
4
Increase engine speed to 2000 RPM.
During extended operation of the A/C
system, does the low side pressure
decrease, possibly accompanied by heavy
frost on the liquid line between the
expansion device and the evaporator?
-
Go to Air
Conditioning
(A/C)
Diagnostics -
Pressure
Zone D
Go to Step 5
1. Refer to the pressures recorded
during the A/C system performance
test.
2. Inspect for the following conditions:
CAUTION:
2008 Chevrolet Silverado 1500
2008 HVAC Heating, Ventilation, and Air Conditioning - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
5
The high side pressure is
slightly greater than the
specified pressure ranges but
still within Zone A on the A/C
Pressure-Zone Classification
Chart in the A/C System
Performance Test. Refer to Air
Conditioning (A/C) System
Performance Test (Diesel
Engine)Air Conditioning
(A/C) System Performance
Test (Gas Engine w/ Electric
Cooling Fan)Air
Conditioning (A/C) System
Performance Test (Gas
Engine w/Engine Driven
Fan) .
The discharge line is hot.
The suction line is cool.
Do the listed conditions exist?
Refer to Moving Parts and Hot
Surfaces Caution .
-
Go to Step 7 Go to Step 6
6
1. Refer to the pressures recorded
during the A/C system performance
test.
2. Inspect for the following conditions:
The low side pressure is
slightly lower than the
specified pressure ranges but
still within Zone A on the A/C
Pressure-Zone Classification
Chart in the A/C System
Performance Test. Refer to Air
Conditioning (A/C) System
Performance Test (Diesel
Engine)Air Conditioning
(A/C) System Performance
-
2008 Chevrolet Silverado 1500
2008 HVAC Heating, Ventilation, and Air Conditioning - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
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