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A/C Performance Test

WARNING:

Review the safety precautions and warnings in this group before performing this procedure. Failure to follow these instructions may result in serious or fatal injury.

CAUTION:

The use of an A/C recycling/charging station for purposes of determining the actual charge level of an A/C system is not recommended. Service recycling/charging stations do not reflect the correct amount of refrigerant charge in the A/C system after a single "reclaim" cycle. Tests have shown that it can take two or more "reclaim" cycles to remove all of the refrigerant charge, depending on the equipment being used. Use only the following procedure for determining the proper charge level.

NOTE:

When connecting the service equipment coupling to the line fitting, verify that the valve of the coupling is fully closed. This will reduce the amount of effort required to make the connection.

  1. Check for Diagnostic Trouble Codes (DTCs) using a scan tool. If no DTCs are found in the A/C heater control, Body Control Module (BCM) or Powertrain Control Module (PCM), go to the next step. If any DTCs are found, repair as required, then proceed to the next step.
  2. Connect a tachometer and a manifold gauge set.
    NOTE:

    The ambient air temperature of the vehicle and the location where the vehicle will be tested must be a minimum of 21°C (70°F) before performing this test. Also the evaporator temperature sensor must be a minimum of 18°C (65°F) for this test as well. Place the vehicle in the testing area until the temperature within the vehicle reaches a minimum of 18°C (65°F).

  3. Operate the heating and A/C system under the following conditions:
    • Engine at normal operating temperature
    • Engine at normal idle speed
    • Door and windows closed
    • Transaxle in Park
    • A/C-heater controls set to Recirculation mode, full cool, panel mode, high blower and with A/C compressor engaged. If the A/C compressor does not engage, see the A/C System Diagnosis table
    • All panel outlet vanes open and positioned straight rearward
    • If equipped with rear A/C, set rear controls to full cool and high blower
  4. Insert a thermometer in the driver side center panel air outlet and operate the A/C system until the thermometer temperature stabilizes or a minimum of 5 minutes.
    NOTE:

    This procedure requires the technician to know what the temperature and relative humidity is at the time of the test. The temperature must be combined with the relative humidity to calculate the apparent ambient temperature ("feels like" temperature), when the temperatures are above 21°C (70°F). Use the current ambient temperature and the relative humidity in your location. This information can be obtained from multiple sources, such as the internet or local news media.

  5. With the A/C clutch engaged, compare the air temperature at the center panel outlet and the compressor discharge pressure (high side) to the A/C Performance Temperature and Pressure chart.
    A/C PERFORMANCE TEMPERATURE AND PRESSURE

    Ambient Air Temperature (Apparent) 21°C
    (70°F)    		 27° C
    (80°F)    		 32°C
    (90°F)    		 38°C
    (100°F)    		 43°C
    (110°F)
    Maximum Allowable Air Temperature at Center Panel Outlet  9°C
    (48°F)    		 9°C
    (48°F)    		 12°C
    (54°F)    		 15°C
    (59°F)    		 24°C
    (75°F)
    Maximum Allowable Air Temperature at Driver Side 2nd Row Headliner Outlet  10°C
    (50°F)    		 13°C
    (55°F)    		 15°C
    (59°F)    		 17°C
    (63°F)    		 24°C
    (75°F)
    Suction Pressure at Service Port (Low Side)  138 to 310 kPa
    (20 to 45 psi)    		 138 to 345 kPa
    (20 to 50 psi)    		 207 to 365 kPa
    (30 to 55 psi)    		 207 to 414 kPa
    (30 to 60 psi)    		 241 to 448 kPa
    (35 to 65 psi)
    Discharge Pressure at Service Port (High Side)  1034 to 1724 kPa
    (150 to 250 psi)    		 1379 to 2068 kPa
    (175 to 300 psi)    		 1551 to 2241 kPa
    (175 to 325 psi)    		 1724 to 2413 kPa
    (250 to 350 psi)    		 2068 to 2758 kPa
    (300 to 475 psi)
  6. If the air outlet temperature fails to meet the specifications in the A/C Performance Temperature and Pressure chart, or if the compressor discharge pressure is high, see the A/C System Diagnosis table.
A/C SYSTEM DIAGNOSIS

Condition Possible Causes Correction
For applications with a fixed displacement compressor, rapid A/C clutch cycling with poor panel outlet temperatures 1. Low refrigerant system charge 1. See Refrigerant System Leaks in this group. Test the refrigerant system for leaks. Repair, evacuate and charge the refrigerant system, if required.
Equal pressures, but the A/C clutch does not engage 1. No refrigerant in the refrigerant system 1. See Refrigerant System Leaks in this group. Test the refrigerant system for leaks. Repair, evacuate and charge the refrigerant system, if required.
2. Open fuse 2. See Wiring Information. Check the fuses. Repair the shorted circuit or component and replace the fuses, if required.
3. Inoperative A/C clutch coil 3. See A/C Compressor in this group. Test the A/C clutch and coil and replace, if required.
4. Inoperative A/C-heater control, PCM or BCM 4. See Group 28 - DTC Based Diagnostics. Test the A/C heater control, PCM or BCM and replace, if required.
5. Inoperative A/C pressure transducer 5. See A/C Pressure Transducer in this group. Test the sensor and replace, if required.
Normal pressures, but A/C Performance Test air temperatures at center panel outlets are too high 1. Excessive refrigerant oil in system 1. See A/C Refrigerant Oil Level in this group. Recover the refrigerant from the refrigerant system and inspect the refrigerant oil content. Restore the refrigerant oil to the proper level, if required.
2. Blend door actuators improperly installed or inoperative 2. See Blend Door Actuator in this group. Inspect the actuators for proper operation and replace, if required.
3. Blend-air doors inoperative or sealing improperly 3. See HVAC Housing in this group. Inspect the blend-air doors for proper operation and sealing. Repair if required.
The low side pressure is normal or slightly low, and the high side pressure is too low 1. Low refrigerant system charge 1. See Refrigerant System Leaks in this group. Test the refrigerant system for leaks. Repair, evacuate and charge the refrigerant system, if required.
2. Refrigerant flow through the A/C evaporator is restricted 2. See A/C Evaporator in this group. Replace the restricted A/C evaporator, if required.
3. Restricted refrigerant flow through the refrigerant lines 3. See Plumbing in this group. Inspect the refrigerant lines for kinks, tight bends or improper routing. Correct the routing or replace the refrigerant line if required.
4. Inoperative A/C compressor 4. See A/C Compressor in this group. Replace the compressor, if required.
The low side pressure is normal or slightly high, and the high side pressure is too high 1. A/C condenser air flow restricted 1. See A/C Condenser in this group. Check the A/C condenser for damaged fins, foreign objects obstructing air flow through the condenser fins, and missing or improperly installed air seals. Clean, repair, or replace components as required.
2. Refrigerant flow through the A/C receiver/drier is restricted 2. See A/C Receiver/Drier in this group. Replace the restricted A/C receiver/drier, if required.
3. Restricted refrigerant flow through the refrigerant lines 3. See Plumbing in this group. Inspect the refrigerant lines for kinks, tight bends or improper routing. Correct the routing or replace the refrigerant line if required.
4. Inoperative radiator cooling fan 4. See Group 7 - Cooling. Test the radiator cooling fan and replace, if required.
5. Refrigerant system overcharged 5. See Refrigerant System Charge in this group. Recover the refrigerant from the refrigerant system. Charge the refrigerant system to the proper level, if required.
6. Air in the refrigerant system 6. See Refrigerant System Leaks in this group. Test the refrigerant system for leaks. Repair, evacuate and charge the refrigerant system, if required.
7. Engine overheating 7. See Group 7 - Cooling. Test the engine cooling system and repair, if required.
The low side pressure is too high, and the high side pressure is too low 1. Accessory drive belt slipping 1. See Group 7 - Cooling. Inspect the accessory drive belt condition and tension. Tighten or replace the accessory drive belt, if required.
2. Inoperative A/C expansion valve 2. See A/C Expansion Valve in this group. Replace the valve, if required.
3. Inoperative A/C compressor 3. See A/C Compressor in this group. Replace the compressor, if required.
4. Restricted refrigerant flow through the refrigerant lines 4. See Plumbing in this group. Inspect the refrigerant lines for kinks, tight bends or improper routing. Correct the routing or replace the refrigerant line if required.
The low side pressure is too low, and the high side pressure is too high 1. Restricted refrigerant flow through the refrigerant lines 1. See Plumbing in this group. Inspect the refrigerant lines for kinks, tight bends or improper routing. Correct the routing or replace the refrigerant line if required.
2. Restricted refrigerant flow through the A/C expansion valve 2. See A/C Expansion Valve in this group. Replace the valve, if required.
3. Restricted refrigerant flow through the A/C condenser 3. See A/C Condenser in this group. Replace the restricted condenser, if required.
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