Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1443 (HVAC SYSTEMS - GENERAL SERVICING)DIAGNOSTIC INFORMATION AND PROCEDURESAIR CONDITIONING (A/C) SYSTEM PERFORMANCE TESTTEST DESCRIPTION
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Test Description
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Test Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
The following test measures the A/C system under the following conditions:
- The current ambient air temperature
- The current ambient air humidity
- The high side pressure of the A/C system
- The low side pressure of the A/C system
- The temperature of the air being discharged into the passenger compartment
The numbers below refer to the step numbers on the diagnostic table.
- 1: This step determines if the A/C system has at least the minimum refrigerant charge to operate the system without damage.
- 2: This step measures the performance of the A/C system.
- 3: This step is to allow for vehicle variations as well as high ambient temperatures.
Air Conditioning (A/C) System Performance Test
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
|
IMPORTANT:
|
||||
| 1 |
|
Above 16° C (60° F): 345 kPa (50 psi) Above 24° C (75° F): 483 kPa (70 psi) Above 33° C (90° F): 690 kPa (100 psi) |
Go to Step 2 | Go to Leak Testing |
| 2 |
IMPORTANT:
Record the relative humidity and the ambient temperature at the time of the test.
IMPORTANT:
When using the print function of the J 43600
for this step, press the RESET button before pressing the PRINT button in order to capture the correct information. See Special Tools and Equipment .
|
- | Go to Step 8 | Go to Step 3 |
| 3 | If the pressures and temperatures recorded do not fall within the specified ranges:
Does all the data recorded fall within the specified ranges of the table below? |
- | Go to Step 8 | Go to Step 4 |
| 4 | Do the high and low side pressures fall within the specified ranges but the outlet temperatures do not? | - | Go to Air Conditioning (A/C) Diagnostics - Pressure Zone A | Go to Step 5 |
| 5 | Is the low side pressure higher than the specified range and the high side pressure within or lower than the specified range? | - | Go to Air Conditioning (A/C) Diagnostics - Pressure Zone B | Go to Step 6 |
| 6 | Are the low and high side pressures both higher than the specified ranges? | - | Go to Air Conditioning (A/C) Diagnostics - Pressure Zone C | Go to Step 7 |
| 7 | Is the high side pressure greater than the specified range, but the low side pressure is within or less than the specified range? | - | Go to Air Conditioning (A/C) Diagnostics - Pressure Zone D | Go to Step 8 |
| 8 | Operate the system in order to verify the test results. Did you find the same results? |
- | System OK | Go to Symptoms - HVAC Systems - Manual in HVAC Systems-Manual or Symptoms - HVAC Systems - Automatic in HVAC Systems-Automatic |
A/C Performance Table
| Ambient Temperature | Relative Humidity | Low Side Service Port Pressure | High Side Service Port Pressure | Maximum Left Center Discharge Air Temperature |
|---|---|---|---|---|
| 13-18° C (55-65° F) | 0-100% | 175-207 kPa (25-30 psi) | 1030-1220 kPa (135-175 psi) | 7° C (45° F) |
| 19-24° C (66-75° F) | Below 40% | 175-254 kPa (25-37 psi) | 1200-1430 kPa (160-200 psi) | 11° C (52° F) |
| Above 40% | 175-262 kPa (25-38 psi) | 1170-1400 kPa (170-210 psi) | 11° C (52° F) | |
| 25-29° C (76-85° F) | Below 35% | 208-288 kPa (30-42 psi) | 1370-1570 kPa (150-190 psi) | 14° C (57° F) |
| 35-50% | 213-292 kPa (31-42 psi) | 1350-1570 kPa (160-200 psi) | 14° C (57° F) | |
| Above 50% | 216-300 kPa (31-44 psi) | 1340-1550 kPa (160-200 psi) | 15° C (59° F) | |
| 30-35° C (86-95° F) | Below 30% | 242-328 kPa (35-48 psi) | 1510-1750 kPa (200-240 psi) | 17° C (63° F) |
| 30-50% | 246-335 kPa (36-49 psi) | 1500-1740 kPa (200-240 psi) | 17° C (63° F) | |
| Above 50% | 252-346 kPa (37-50 psi) | 1490-1730 kPa (200-240 psi) | 19° C (66° F) | |
| 36-41° C (96-105° F) | Below 20% | 281-366 kPa (41-53 psi) | 1680-1920 kPa (240-280 psi) | 19° C (66° F) |
| 20-40% | 285-374 kPa (41-54 psi) | 1670-1920 kPa (245-285 psi) | 21° C (70° F) | |
| Above 40% | 292-383 kPa (42-56 psi) | 1670-1910 kPa (250-265 psi) | 22° C (72° F) | |
| 42-46° C (106-115° F) | Below 20% | 322-400 kPa (47-58 psi) | 1850-2070 kPa (250-290 psi) | 22° C (72° F) |
| Above 20% | 326-410 kPa (47-60 psi) | 1840-2060 kPa (260-300 psi) | 23° C (73° F) | |
| 47-49° C (116-120° F) | Below 30% | 360-426 kPa (52-62 psi) | 1990-2150 kPa (290-330 psi) | 24° C (75° F) |
A/C Performance Table - with Rear A/C
| Ambient Air Temperature | Relative Humidity | Service Port Pressure | Maximum Discharge Air Temperature | ||
|---|---|---|---|---|---|
| Low Side | High Side | Left Center | Rear Center | ||
| 13-18° C (55-65° F) | 0-100% | 184-273 kPa (27-40 psi) | 600-1080 kPa (87-157 psi) | 19° C (66° F) | 17° C (62° F) |
| 19-24° C (66-75° F) | Below 40% | 227-335 kPa (33-49 psi) | 720-1210 kPa (105-176 psi) | 19° C (66° F) | 20° C (68° F) |
| Above 40% | 234-349 kPa (34-51 psi) | 840-1330 kPa (122-193 psi) | 22° C (72° F) | 21° C (70° F) | |
| 25-29° C (76-85° F) | Below 35% | 286-383 kPa (42-56 psi) | 1050-1440 kPa (152-209 psi) | 21° C (70° F) | 23° C (73° F) |
| 35-50% | 293-390 kPa (43-57 psi) | 1110-1470 kPa (161-213 psi) | 22° C (72° F) | 23° C (73° F) | |
| Above 50% | 298-403 kPa (43-59 psi) | 1160-1550 kPa (168-225 psi) | 24° C (75° F) | 24° C (75° F) | |
| 30-35° C (86-95° F) | Below 30% | 334-440 kPa (49-64 psi) | 1310-1720 kPa (190-250 psi) | 24° C (75° F) | 27° C (81° F) |
| 30-50% | 341-452 kPa (51-68 psi) | 1340-1750 kPa (195-254 psi) | 25° C (77° F) | 27° C (81° F) | |
| Above 50% | 350-469 kPa (51-68 psi) | 1390-1800 kPa (202-261 psi) | 27° C 81° F) | 28° C (82° F) | |
| 36-41° C (96-105° F) | Below 20% | 388-492 kPa (56-71 psi) | 1600-2000 kPa (232-290 psi) | 27° C (81° F) | 30° C (86° F) |
| 20-40% | 394-506 kPa (57-73 psi) | 1620-2020 kPa (235-293 psi) | 28° C (82° F) | 31° C (88° F) | |
| Above 40% | 406-520 kPa (59-76 psi) | 1660-2040 kPa (241-296 psi) | 29° C (84° F) | 32° C (90° F) | |
| 42-46° C (106-115° F) | Below 20% | 445-541 kPa (65-79 psi) | 1910-2260 kPa (277-328 psi) | 30° C (86° F) | 34° C (93° F) |
| Above 20% | 452-557 kPa (66-81 psi) | 1920-2260 kPa (279-328 psi) | 31° C (88° F) | 34° C (93° F) | |
| 47-49° C (116-120° F) | Below 30% | 501-579 kPa (73-84 psi) | 2180-2410 kPa (316-350 psi) | 32° C (90° F) | 36° C (97° F) |
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.