Commander 2006-2007

Air Conditioning System Diagnosis


Refer to the applicable warnings and cautions for this system before performing the following operation. Failure to follow the warnings and cautions could result in possible serious or fatal injury.

The use of an A/C recycling/charging station for purposes of determining the actual charge level of an A/C system is not recommend. 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 takes up to 3 or 4 -reclaim- cycles to remove all of the refrigerant charge. Use only the following procedure for determining the proper charge level.

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.

The work area ambient temperature and the evaporator temperature must be above 65°F (18°C) prior to conducting the A/C Performance Test.

  1. If no Diagnostic Trouble Codes (DTCs) are found in the A/C-heater control or the Powertrain Control Module (PCM), go to Step No. 2. If any DTCs are found, repair as required, then proceed to Step No. 2.
  3. Connect a tachometer and a manifold gauge set or an A/C recycling/charging station.
  5. Operate the heating-A/C system under the following conditions:

    Engine at 1,000 rpm at operating temperature
    Doors and windows closed
    Transmission in Park
    A/C-heater controls set to Recirculation mode (max-A/C), 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 chart

  7. Insert a thermometer in the driver side center panel air outlet and operate the A/C system until the thermometer temperature stabilizes.
  9. With the A/C compressor clutch engaged, compare the air temperature at the center panel outlet and the A/C compressor discharge pressure (high side) to the A/C Performance Temperature and Pressure chart. The compressor clutch may cycle, depending upon the ambient temperature and humidity. If the clutch cycles, use the readings obtained before the clutch disengaged.

    Click image to see an enlarged view

    Fig. A/C Performance Temperature and Pressure

  11. If the air outlet temperature fails to meet the specifications in the A/C Performance Temperature and Pressure chart, or if the A/C compressor discharge pressure is high, refer to the A/C System Diagnosis chart.

    Click image to see an enlarged view

    Fig. A/C System Diagnosis