Protective function during blocked air conditioning compressor

A thermal safeguarding in the moulding compound of the coil in the magnetic coupling serves as a protective function during a blocked air conditioning compressor.

If the thermal load on the magnetic coupling reaches a certain temperature (189 °C ± 10 K), the thermal safeguarding responds. As a result, the voltage supply for the magnetic coupling is interrupted. The magnetic coupling is open when de-energized. By doing this, the transmission of the torque from the belt pulley to the driver, that is connected with the shaft of the air conditioning compressor, is interrupted.

If the thermal safeguarding responds, the air conditioning compressor must be replaced in the service. Reason: The thermal safeguarding is not reversible and cannot be exchanged as an individual component.

Failure of the component: 

The following behavior can be expected if the magnetic coupling (electrical activation) fails:

• Fault code entry in the junction box electronics (JBE) or in the front electronic module (FEM) or in the Body Domain Controller (BDC)
• The magnetic coupling is open when de-energized. By doing this, the air conditioning compressor is not driven. Air conditioning operation is not possible.

The following behavior can be expected if the electrical control valve (electrical activation) fails:

• Fault code entry in the junction box electronics (JBE) or in the front electronic module (FEM) or in the Body Domain Controller (BDC)
• The electrical control valve is open when de-energized. Out of this, a minimum displacement results.

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