Service Stall Test (Normal & High Humidity Conditions)
WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
This test must be performed in a service stall environment that protects the vehicle from wind that could cause incorrect pressure or temperature.
- Start engine and warm to normal operating temperature.
- Install thermometer in right center outlet.
- Open doors and windows to stabilize interior temperature with outside ambient air temperature.
- Depress recirculation switch.
- Set temperature knob to full cold.
- Select 3rd blower speed.
- Depress A/C switch.
- Run engine at 2000 RPM.
- Continue running until system pressures and outlet temperature stabilizes (usually 5 to 7 minutes).
- Record A/C system pressures and outlet temperatures every 5 minutes.
Under normal conditions, compare readings to normal A/C system performance specifications table. See Fig 1 . Under high humidity condition, compare readings to high humidity A/C system performance specifications table. See Fig 2 . High humidity conditions affect the system performance by increased heat load on the system. This extra heat load will increase the discharge pressure and the outlet temperature. High humidity is defined as a relative humidity greater than
- 70 percent at 70°F (21°C).
- 60 percent at 80°F (27°C).
- 50 percent at 90°F (32°C).
- 40 percent at 100°F (38°C).
As a general rule, a normal system operating under high humidity conditions will produce an outlet temperature of at least 20°F less than the ambient air temperature.