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Air Conditioning (A/C) System Performance Test (R-134a)

WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.

Technicians repairing or servicing motor vehicle air conditioning (MVAC) must be trained and certified by an EPA approved organization. Certification is obtained by passing an EPA approved examination. (http://www.epa.gov/ozone/title6/609/technicians/609certs.html).

This test measures the operating efficiency of the A/C system under the following conditions:

Test Description 

The numbers below refer to the step numbers on the diagnostic table.

  1. 1 

    This step determines if the A/C system has at least the minimum refrigerant charge required to operate the system without damage.

  2. 2 

    This step measures the performance of the A/C system.

  3. 3 

    This step is to allow for vehicle variations as well as high ambient temperatures.

Step Action Values Yes No
NOTE:
  • The ambient air temperature must be at least 16°C (60°F).
  • Do not induce additional air flow across the front of the vehicle during the test.
  • If you were sent here from a DTC diagnostic table, clear the DTC upon completion of this test.
1 
  1. Park the vehicle inside or in the shade.
  2. Open the windows in order to ventilate the interior of the vehicle.
  3. If the A/C system was operating, allow the A/C system to equalize for about 2 minutes.
  4. Turn OFF the ignition.
  5. Install the J-43600  Acr2000 Air Conditioning Service Center ACR 2000 Air Conditioning Service Center.
  6. Record the ambient air temperature and humidity.
  7. Record the low and high side STATIC pressure readings.
Are both the low side and high side pressures within the specified value?		 More than 16°C (60°F) - 345 kPa (50 psi)
More than 24°C (75°F) - 483 kPa (70 psi)
More than 33°C (90°F) - 690 kPa (100 psi)		 Go to Step 2  Go to Leak Testing (R-134a) 
2 
    NOTE:

    Record the relative humidity and the ambient air temperature at the time of the test.

  1. Close the vehicle doors and windows.
  2. Open the drivers door window 12.7-15.2 cm (5-6 in).
  3. Select the following HVAC control settings:
    • The A/C is ON.
    • The coldest temperature setting
    • The maximum blower speed
    • Recirculation mode
    • The instrument panel (I/P) outlet mode
    • All I/P outlets are OPEN.
  4. Install thermometers in the left and right center panel air outlets.
  5. Apply the parking brake.
  6. Place the transaxle/transmission in one of the following positions:
    • PARK (Automatic)
    • NEUTRAL (Manual)
  7. Start the engine and warm to operating temperature.
  8. Operate the A/C system for 5 minutes.
  9. Inspect A/C components for the following conditions:
    • Abnormal frost areas
    • Unusual noises
  10. Record the following information:
    • The panel outlet air temperatures
    • The low-side pressure
    • The high-side pressure
  11. Compare the low and high side pressures and the panel output temperatures to the A/C Performance Table below.
Does all the data recorded fall within the specified ranges of the A/C Performance Table below?		 - Go to Step 5  Go to Step 3 
3  If the pressures and temperatures recorded do not fall within the specified ranges:
  1. Continue to operate the A/C system for an additional 5 minutes.
  2. Record the pressures and temperatures again.
  3. Compare the low and high side pressures and the panel output temperature to the A/C Performance Table below.

Does all the data recorded fall within the specified ranges of the A/C Performance Table below?		 - Go to Step 5  Go to Step 4 
4 Perform the necessary repairs. Refer to A/C Diagnostics Chart .
Is the action complete?		 - Go to Step 5  -
5 Operate the system in order to verify the test results.
Did you find the same results?		 - System OK Go to Symptoms - 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 (55-64°F) 0-100% 186-289 kPa (27-42 psi) 930-1260 kPa (135-183 psi) 10°C (50°F)
19-24°C (66-75°F) Less than 40% 186-289 kPa (27-42 psi) 909-1212 kPa (132-176 psi) 9°C (48°F)
Greater than 40% 213-323 kPa (31-47 psi) 1019-1329 kPa (148-193 psi) 13°C (55°F)
25-29°C (77-84°F) Less than 35% 220-310 kPa (32-45 psi) 1061-1288 kPa (154-187 psi) 12°C (54°F)
35-50% 241-323 kPa (35-47 psi) 1123-1322 kPa (163-192 psi) 13°C (55°F)
Greater than 50% 254-351 kPa (37-51 psi) 1157-1391 kPa (168-202 psi) 15°C (59°F)
30-35°C (86-95°F) Less than 30% 248-337 kPa (36-49 psi) 1157-1391 kPa (168-202 psi) 14°C (57°F)
30-50% 261-358 kPa (38-52 psi) 1198-1419 kPa (174-206 psi) 15°C (59°F)
Greater than 50% 282-378 kPa (41-55 psi) 1240-1460 kPa (180-212 psi) 18°C (64°F)
36-41°C (97-106°F) Less than 20% 282-365 kPa (41-53 psi) 1288-1508 kPa (187-219 psi) 17°C (63°F)
20-40% 289-378 kPa (42-55 psi) 1302-1522 kPa (189-221 psi) 18°C (64°F)
Greater than 40% 303-392 kPa (44-57 psi) 1329-1529 kPa (193-222 psi) 19°C (66°F)
42-46°C (108-115°F) Less than 20% 316-392 kPa (46-57 psi) 1419-1612 kPa (206-234 psi) 18°C (64°F)
Greater than 20% 323-406 kPa (47-59 psi) 1433-1612 kPa (208-234 psi) 20°C (68°F)
47-49°C (117-120°F) Below 30% 351-427 kPa (51-62 psi) 1529-1701 kPa (222-247 psi) 22°C (72°F)
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