Performance Test - Service Stall

Service Stall Test
Record the manifold gauge pressures, outlet temperature and ambient air temperature with the following preset vehicle conditions:

IMPORTANT: If the ambient air temperature is lower than 5° (40°F), the A/C compressor will not be enabled.

1. Install thermometer in right center outlet.
2. Open doors and windows to stabilize interior temperature with outside ambient air temperature.
3. Depress recirc button.
4. Set temperature knob to full cold.
5. Select 3rd blower speed.
6. Depress A/C button.
7. Engine fully warmed up and running at 2000 rpm.
8. Continue running until system pressures and outlet temperature stabilize. Usually five to seven minutes.
9. Record pressure and temperatures.
10. Compare readings to normal system performance charts then continue down diagnostic flow chart.


Normal System Performance

Normal System Performance Service Stall:

IMPORTANT: To ensure accurate pressure and temperature readings make sure the vehicle is properly set up to run the performance test. (Refer to vehicle set up.) All test parameters must be followed to obtain accurate readings.

Confirm system performance by touching the suction and discharge pipes at the compressor. The suction pipe will be cold and the discharge pipe will be hot.

IMPORTANT: Use a refrigerant identifier to verify refrigerant purity. Non-condensable gases or refrigerant substitutes will affect system pressure/temperature readings.


Normal System Performance - High Humidity

Normal System Performance Service Stall High Humidity:

^ High humidity conditions affect system performance by increased heat load on the system. High humidity is defined as a relative humidity higher than 70 percent at 21°C (70°F), 60 percent at 27°C (80°F), 50 percent at 32°C (90°F), and 40 percent at 38°C (100°F).
^ This chart illustrates the effect high humidity has on the Saturn air conditioning system. Use this chart to determine normal system performance under high humidity conditions.
^ As a general rule normal systems operating under high humidity conditions will produce an outlet temperature of at least 20 degrees Fahrenheit below ambient air temperature