Grand Prix V6-3100 3.1L VIN M SFI (1996)
A/C Signal: Description and Operation
Compressor Control Signal
DESCRIPTION
The air conditioning system uses a compressor with variable displacement. This compressor is referred to as the V-5 type compressor. The V-5
compressor meets A/C requirements without cycling. The A/C compressor operation is controlled by the Powertrain Control Module (PCM) for the
following reasons:
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Improved idle quality during compressor clutch engagement.
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Improved wide open throttle performance (WOT).
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Protects the A/C compressor from operation with incorrect refrigerant pressures.
The A/C clutch electrical system consists of the following components:
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The A/C control head and/or the A/C programmer.
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The A/C refrigerant pressure sensor.
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The A/C compressor clutch.
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The A/C compressor clutch relay.
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The PCM.
OPERATION
When an A/C mode is selected at the A/C control head, the A/C programmer provides a 12 volt signal to the A/C request circuit. The PCM monitors the
A/C request circuit and controls the A/C compressor relay based on the A/C request signal. This allows the PCM to increase the engine idle speed lust
prior to A/C clutch engagement for better idle quality. In addition, the PCM will command the cooling fans ON during A/C operation. The PCM also
monitors the A/C refrigerant pressure sensor circuit. If the A/C refrigerant pressure is too high or low, the PCM will disable the A/C compressor relay.
The PCM will enable the A/C compressor clutch whenever the engine is running and the A/C has been requested unless one or more of the following
conditions are present:
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Throttle angle is greater than 90%.
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A/C head pressure is greater than 427 psi (4.27 volts) or less than 41 psi (0.35 volt) as determined by the A/C refrigerant pressure sensor.
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Ignition voltage is less than 9.5 volts.
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Engine speed is greater than 6900 RPM for longer than 5 seconds.
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ECT is greater than 121°C (250°F).
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IAT is less than 0°C (32°F).
Any of the conditions described above will inhibit A/C compressor relay operation.
