Explanation of the Possible Operating Status of the Electric A/C Compressor (Ekk)

Explanation of the possible operating status of the electric A/C compressor (EKK):


- Electric A/C compressor off
Electric A/C compressor is not switched on.

- EKK ready for operation
Electric A/C compressor is ready for operation and switched on

- EKK fault
A fault was detected in the electric A/C compressor. The electric A/C compressor is switched off.

- EKK in status: Power reduction
No fault. This is a protective function of the electric A/C compressor. The electric A/C compressor is in the state of permissible power reduction (degradation) due to external marginal conditions. These marginal conditions only occur for a limited time. If the marginal conditions are permitted again, the operation of the electric A/C compressor is continued again at full power.

- EKK in status: Active short circuit
A short circuit is actively established in the electric A/C compressor to discharge the capacitors. This is required for the measurement of the insulation resistance.

- EKK Stop
The electric A/C compressor.
No fault. This is a protective function of the electric A/C compressor. The electric A/C compressor is in the state of permissible switch-off due to external marginal conditions. These marginal conditions only occur for a limited time. If the marginal conditions are permitted again, the operation of the electric A/C compressor is continued again.

- O.K.
No fault status available.

Explanation of the possible fault status during operation of the electric A/C compressor:
- Switch-off due to start-up fault
An internal mechanical fault was found.
Measure:
- The electric A/C compressor must be replaced.

- Switch-off due to excess torque
No fault with electric A/C compressor. The start-up torque of the electric A/C compressor is too high.
Possible causes:
- Too much refrigerant in the refrigerant circuit.
- Refrigerant pressure is too high.
- Very high ambient temperature in the engine compartment.
- Refrigerant shutoff valves closed during operation.

Measures:
- Check amount of refrigerant
- Allow engine compartment to cool
- Check refrigerant shutoff valve

- Switch-off due to supply fault
The electric A/C compressor identified sporadic faults on the low-voltage side.
Possible causes:
- Low-voltage supply faulty
- Lines or connector defective
Measures:
- Carry out energy diagnosis on low-voltage side
- Check lines and plug-in contacts of voltage supply.

- Switch-off due to fault in sensor system
An internal electrical fault was found.
Measure:
- The electric A/C compressor must be replaced.

- Switch-off due to fault with inverter
No fault with electric A/C compressor.
Possible causes:
Too high a temperature of the printed circuit board.

Measures:
- Switch off heating and air-conditioning system, allow to cool for at least 10 minutes and then repeat activation.

- Switch-off due to critical excess temperature
No fault with electric A/C compressor. The printed circuit board of the electric A/C compressor becomes too warm.
Possible causes:
- Too little refrigerant in the refrigerant circuit.
- Very high ambient temperature in the engine compartment.

Measures:
- Check amount of refrigerant
- Allow engine compartment to cool
- Allow electric A/C compressor to cool

- Switch-off due to short circuit
An internal electrical fault was found.
Measure:
- The electric A/C compressor must be replaced.

- Switch-off due to LIN communication fault
Sporadic communication faults identified on the local interconnect network bus.
Possible cause:
- Local interconnect network bus line defective (sporadic short circuit or open circuit)
- EMC interference

Measure:
- Check LIN bus line.

- Switch-off due to over/ undervoltage
No fault with electric A/C compressor. The voltage of the high-voltage battery is too high or too low.
Possible cause:
- Discharged high-voltage battery
Measure:
- Perform energy diagnosis.

- Very high current identified
No fault with electric A/C compressor but permissible operating condition.
Possible cause:
- Refrigerant pressure too high.
Measure:
- No measure required. The refrigerant pressure is reduced by the power reduction of the electric A/C compressor.