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Air Conditioning (A/C) System Performance Test

WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
    IMPORTANT: Record the ambient temperature conditions and the relative humidity at the time of the test.
  1. Park the vehicle inside or in the shade. The ambient temperature must be at least 21° C (70° F).
  2. Open the windows in order to ventilate the interior.
  3. Vent the engine exhaust.
  4. Open the hood and install the high and low side pressure gauges of the J 39183-C  . See Special Tools and Equipment .
  5. Route the pressure gauge hoses and close the hood to the safety latch position.
  6. Record the ambient temperature outside.
  7. Record the relative humidity.
  8. Turn the A/C on, set the mode to the VENT position, the temperature to the coldest position, the fresh/recirculation to recirculation, the blower speed to high and open the windows.
  9. Open the A/C air outlet deflectors.
  10. Place a J 6742-03  thermometer in the left center A/C outlet. See Special Tools and Equipment .
  11. Place the transaxle in PARK and start the engine, stabilize the engine at 1500 RPM.
  12. Run the A/C system about 5 minutes or until the outlet air reaches the lowest temperature.
  13. Record the outlet air temperature and the high side and the low side pressures.
  14. Turn the engine off and compare the readings with the data in the A/C Performance Table. A normally operating A/C system should not exceed levels shown. If the readings exceed the table limits, refer to TXV Air Conditioning (A/C) System Diagnosis (Insufficient Cooling)  or TXV Air Conditioning (A/C) System Diagnosis (Reference Table) . Also refer to Symptoms - HVAC Systems - Manual in HVAC Systems - Manual.
A/C Performance Table

Engine Speed (rpm) Relative Humidity (%) Ambient Air Temperature Left Center Air Outlet Temperature Low Side Pressure High Side Pressure
° F ° C ° F ° C psig kPa psig kPa
1500 40 70 21 N/A N/A N/A N/A N/A N/A
80 27 50 10 32 0 240 1655
90 32 57 14 40 4 281 1937
100 38 64 18 46 8 319 2200
110 43 71 22 55 13 367 2530
115 46 76 25 63 17 445 3068
80 70 21 49 10 32 0 229 1579
80 27 57 14 39 4 260 1793
90 32 64 18 48 9 297 2048
100 38 75 24 62 17 381 2627
110 43 83 28 70 21 425 2930
115 46 N/A N/A N/A N/A N/A N/A
Refrigerant-134a Pressure-Temperature Relationship

° C ° F kPa psig ° C ° F kPa psig
DEFINITION: This table indicates the pressure of the Refrigerant-134a at various temperatures. For instance, a drum of refrigerant at room temperature of 26.6° C (80° F) will have a pressure of 595.6 kPa (86.4 psi). If the refrigerant is heated to 51.6° C (125° F), the pressure will increase to 1278.8 kPa (185.5 psi). The refrigerant also can be used conversely in order to determine the temperature at which the Refrigerant-134a boils under various pressures. For example, at a pressure of 188.2 kPa (27.3 psi), the Refrigerant-134a boils at 0° C (32° F).
- 15.5 60 392.3 56.9
-23.3 -10 12.4 1.8 18.3 65 438.2 63.6
-20.5 -5 27.0 3.9 21.1 70 487.3 70.7
-17.7 0 43.2 6.3 23.8 75 539.7 78.3
15.0 5 60.8 8.8 26.6 80 595.6 86.4
-12.2 10 80.1 11.6 29.4 85 655.1 95.0
9.4 15 101.3 14.7 32.2 90 718.5 104.2
-6.6 20 124.3 18.0 35.0 95 785.6 113.9
-3.8 25 149.4 21.7 37.7 100 856.9 124.3
-1.1 30 176.6 25.6 40.5 105 932.3 135.2
0.0 32 188.2 27.3 43.3 110 1012.1 146.8
1.6 35 206.2 29.9 46.1 115 1096.4 159.0
4.4 40 238.0 34.5 48.8 120 1185.2 171.9
7.2 45 272.5 39.5 51.6 125 1278.8 185.5
10.0 50 309.5 44.9 54.4 130 1377.3 199.8
12.7 55 349.4 50.7 60.0 140 1589.6 230.5
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