The compressor for the air conditioning (A/C) system is driven by the engine through the following components:
• | The belt drive |
• | The A/C compressor clutch. |
When the A/C is not required, the clutch allows the compressor to be disengaged.
Battery voltage is supplied to the heater and A/C controls selector switch through HTR-A/C (fuse 12) and CKT 141 (BRN) when the ignition switch is placed in the RUN position.
An A/C request signal is selected when one of the following A/C functions is selected:
• | MAX |
• | NORM |
• | BI-LEVEL |
• | BLEND |
• | DEF |
The A/C request signal is created by passing battery voltage to the vehicle control module (VCM). The path for the request follows the following route:
The VCM monitors the low pressure switch in the system through CKT 603 (DK GRN). The VCM disables the A/C operation is the pressure drops below a predetermined level.
The VCM produces an A/C enable signal on CKT 459 (DK GRN/WHT) when the A/C request signal is generated. The A/C enable signal will provide a ground for the A/C enable relay coil. Voltage is provided through CKT 639 (PNK) from the IGN-E fuse. the voltage will cause a current flow through the coil of the relay . The current will energize the relay. When the relay contacts are closed the battery voltage will be provided through the following route:
The A/C compressor coil is grounded by CKT 850 (BLK). The clutch will engage when the current is flowing.
The A/C compressor clutch diode is connected across the A/C compressor coil circuit. The magnetic field around the clutch will collapse when the clutch is de-energized. When the clutch is de-energized, an induced voltage in the clutch coil is generated. The diode provides a path for the current, which is a result of the induced voltage, so that there is no damage to the other circuit components.