System Performance Test

Tools Required
J 39500-B ACR4 Station

Before you perform the A/C system performance test, perform a functional test in order to ensure that the following conditions exist.

^ The air delivery system valves are functioning.
^ The routing air passes through the evaporator to the outlets.

Refer to the applicable charts:

Performance testing measures the A/C system operating efficiency by comparing the following figures:

^ The ambient air temperature
^ The ambient air humidity
^ The pressure at the high-pressure side of the refrigeration system
^ The pressure at the low-pressure side of the refrigeration system
^ The temperature of the air being discharged into the passenger compartment
1. Park the vehicle inside or in the shade.
2. Open the windows in order to ventilate the interior of the vehicle.
3. Vent the engine exhaust.
4. Open the hood.
5. Install the the following gauges.
Route the lines over the rear hood seal.
Tape the gauges to the windshield for viewing by the driver:
^ The high-side pressure gauge
^ The low-side pressure gauge
6. Close the hood.
7. Record the ambient temperature at the vehicle.

Important: Record the relative humidity and the ambient temperature AT THE TIME OF THE TEST.

8. Record the relative humidity, using one of the following methods:
^ Use a psychrometer.
^ Consult the local weather bureau.
9. Close the doors and windows.
10. Set the mode control to the following settings:
^ The A/C control set to A/C
^ The blower control on HIGH
^ The temperature controls on FULL COLD
11. Open the A/C outlets.
12. Place the thermometer in the right center A/C outlet.
13. Place the transaxle in one of the following positions:
^ PARK
^ NEUTRAL
14. Start the engine.
15. Stabilize the engine at 2000 RPM. Then, start the timer.
16. Run the A/C system until the outlet air reaches the lowest temperature. This will take about 3 minutes.
17. Record the following information:
^ The outlet air temperature
^ The high-side pressure
^ The low-side pressure
18. Turn the engine OFF.
19. Compare the readings with the upper limit data that is located in the A/C Performance Test table below. A normally operating A/C system should not exceed the levels that are shown in the table.
20. If you suspect a malfunction in the refrigerant system due to abnormal system pressures, perform the following steps:
^ Inspect the outer surfaces of the radiator and condenser cores to ensure that the air flow is not blocked by any of the following objects. Inspect between the condenser and the radiator, as well as the outer surfaces:
- Dirt
- Leaves
- Other foreign material
^ Inspect for restrictions in the following areas:
- The evaporator core
- The condenser core
^ Inspect for kinks in the following areas:
- The evaporator core hoses or tubes
- The condenser core hoses or tubes
^ Inspect for refrigerant leaks.
^ Inspect all of the air ducts for the following situations.
Low air flow rate may indicate a restricted evaporator core:
- Leaks
- Restrictions
^ Inspect for compressor clutch slippage.
^ Inspect for the improper drive belt tension.
^ Inspect for a plugged accumulator.
^ Inspect for a plugged expansion (orifice) tube.