A/C Signal: Testing and Inspection

The Powertrain Control Module (PCM) will energize the A/C clutch whenever the engine is running less than 3800 RPM and A/C has been requested unless any of the following conditions are met:

^ Wide Open Throttle (WOT).
^ A/C head pressure greater than 429 psi or less than 0 psi (as determined by the A/C refrigerant pressure sensor),
^ Low ignition voltage.
^ Engine speed greater than 5250 RPM for 30 seconds.
^ Engine Coolant Temperature (ECT) greater than 124°C (255°F).

Chart C-10 should be used for diagnosing the electrical portion of the A/C circuit. Refer to Heating and Air Conditioning for diagnosing the refrigerant portion of the system.

The Tech 1 will be used in diagnosing the system, as it has the ability to display the A/C request input to the PCM, A/C compressor status, A/C system pressure, as well as displaying when the PCM has commanded the A/C clutch "ON."