Chevrolet Silverado / GMC Sierra. Service 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