Compressor Clutch: Description and Operation

Purpose
- Connecting the vehicle engine with the A/C compressor
- Switching off the A/C compressor in the event of a mechanical defect.






Electromagnetic clutch (A9k1)


Design
The pulley (1) on the A/C compressor drive shaft (4) is driven by a poly-V-belt. It turns on the ball bearing (3) around the magnetic coil (5) fastened to the A/C compressor housing. The pressure plate (6) with rubber insert (7) is connected to the A/C compressor drive shaft (4) by splines (8) allowing it to move in the axial direction.


Function
The pushbutton control module actuates the electromagnetic clutch (A9k1) and the magnetic coil (5) receives power in order to start up the A/C compressor. The magnetic force pulls the pressure plate (6) against the rubber insert (7) and holds it tight. This connects the vehicle engine with the A/C compressor. When the power to the magnetic coil (5) is switched off, the pressure plate (6) is pressed away from the rubber insert (7) to its non-actuated position and the connection is interrupted.

To prevent damaging the poly-V-belt, in the event of a mechanical defect in the A/C compressor, the electromagnetic clutch releases automatically. In the event of a mechanical defect, the A/C compressor becomes hard to turn or locks up completely. The heat produced on the friction surface causes the melting safety device (2) in the magnetic coil (5) to melt. The power to the magnetic coil (5) is interrupted and the compressor is disconnected from the engine.