A/C power output DDE 4.0

The A/C compressor is switched on and off by the DDE control module. The DDE control module receives a message from the heating and A/C control module as to whether the air conditioning system button is pressed and whether the heating and A/C control module is requesting that the compressor be switched on. If a request is received to switch on the A/C compressor, the DDE control module checks whether conditions that do not permit the compressor to be switched on apply and sends a corresponding message back to the heating and air conditioning control module. Switch-on of the A/C compressor is inhibited by the DDE control module under following conditions:

• Start-off status:
  Road speed < 10 km/h AND
  Accelerator pedal > 60 % AND
  Engine speed < 1800 rpm
  
• Acceleration:
  Accelerator pedal change > 400%/second AND
  Engine speed < 3000 rpm
  
• Coolant temperature > 117°C
  
• Throttle dip:
  Engine speed < 650 rpm
  
• while starting
  
• Fault code stored in DDE:
  Fault code 500 ”Road speed signal” OR
  Fault code 120, 220 ”Pedal-position sensor”
  

Troubleshooting

The line between the DDE control module and heating and air conditioning control module is monitored for short-circuit and open circuit. Fault code 3515 ”A/C power output” is stored in the case of defect.