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Display group "003” > < Display group "002”

A4 Mk2

Explanatory notes on compressor shutoff criterion for display zones “1....4” of display group “002”
Explanatory notes on compressor shutoff criterion for display zones “1....4” of display group “002”
  Note
The numbers not listed (e.g. “13”) are not assigned a compressor shutoff criterion at present.
   
Display zoneCompressor shutoff criterion codeSignificanceCause of trouble/fault remedy
1...40Compressor on
t  No compressor shutoff criterion detected
–  If the compressor is not switched on, interrogate the fault memory → Chapter and perform final control diagnosis → Chapter and electrical checks → Chapter.
 1* → AnchorCompressor off
t  Pressure in refrigerant circuit has been or is too high
–  Fault rectification → Chapter and Electrical checks → Chapter
–  Current measured value of high-pressure sender -G65- → Anchor and → Anchor
–  Ambient conditions under which pressure was last not OK → Chapter
 2Reduced compressor output
t  The relevant engine control unit requests the operating and display unit, Climatronic control unit -J255- to reduce the compressor output.
t  The operating and display unit, Climatronic control unit -J255- regulates the current for the air conditioning system compressor regulating valve -N280- to approx. 300 mA.
t  The engine control unit has established that the torque for the air conditioner compressor must be reduced to the lowest level still possible for better acceleration or on account of a fault in the engine management system.
–  Interrogate fault memory of engine control unit → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051, → Ignition and injection system; Rep. Gr.01 or → Diesel glow plug and injection system; Rep. Gr.01

   
Display zoneCompressor shutoff criterion codeSignificanceCause of trouble/fault remedy
1...43* → AnchorCompressor off
t  Pressure in refrigerant circuit has been or is too low
–  Fault rectification → Chapter and Electrical checks → Chapter
–  Current measured value of high-pressure sender -G65- → Anchor and → Anchor
 4Compressor off
t  A fault preventing activation of the compressor has been entered in the fault memory of the operating and display unit, Climatronic control unit -J255-.
–  Fault rectification → Chapter
 5Compressor off 
  
t  Engine speed less than 300 rpm
–  Start engine
  
t  No engine speed detected
t  No information received via convenience data bus system
–  Interrogate fault memory → Chapter
t  No engine speed signal output by engine control unit or control unit in dash panel insert -J285-
–  Check engine speed → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051 and → Electrical system; Rep. Gr. 90

   
Display zoneCompressor shutoff criterion codeSignificanceCause of trouble/fault remedy
1...46Compressor off 
  
t  Compressor switched off by way of Econ button of operating and display unit, Climatronic control unit -J255-
–  Switch on compressor
  
t  Following replacement of operating and display unit, Climatronic control unit -J255-, “Basic setting” was not performed
–  Perform basic setting for air conditioner as specified → Chapter.
 7Compressor off
t  Air conditioner switched off by way of Off button of operating and display unit, Climatronic control unit -J255-
–  Vehicle with no air quality sensor -G238-
t  Air conditioner switched off by way of Minus button for fresh air blower of operating and display unit, Climatronic control unit -J255-
–  Vehicle with air quality sensor -G238-
–  Switch on air conditioner (e.g. by way of Auto button of operating and display unit, Climatronic control unit -J255-)

   
Display zoneCompressor shutoff criterion codeSignificanceCause of trouble/fault remedy
1...48Compressor off 
  
t  Vehicle with no air quality sensor -G238-
t  Vehicle with air quality sensor -G238-, however recirculated-air mode not requested by air quality sensor -G238- or “automatic air recirculation” function deactivated.
–  Measured ambient temperature less than 5 °C
–  Measured ambient temperature had been less than 2 °C and has not risen above 5 °C since
t  Ambient temperature less than 5 °C
–  Move vehicle into a heated area for checking
t  The control unit in dash panel insert -J285- or the fresh-air intake duct temperature sensor -G89- is supplying incorrect values
–  Check the measured values of the ambient temperature sensors -G17- (transmitted via convenience data bus system by control unit in dash panel insert -J285-) and the fresh-air intake duct temperature sensor -G89- (display group “010”) → Chapter
  
t  Vehicle with air quality sensor -G238-, “automatic air recirculation” function activated and recirculated-air mode requested by air quality sensor -G238-
–  Measured ambient temperature less than -8 °C
–  Measured ambient temperature had been less than -8 °C and has not risen above -5 °C since
t  Ambient temperature less than -5 °C
t  Ambient temperature less than 5 °C and engine cold
–  Move vehicle into a heated area for checking
t  The control unit in dash panel insert -J285- or the fresh-air intake duct temperature sensor -G89- is supplying incorrect values
–  Check the measured values of the ambient temperature sensors -G17- (transmitted via convenience data bus system by control unit in dash panel insert -J285-) and the fresh-air intake duct temperature sensor -G89- (display group “010”) → Chapter

   
Display zoneCompressor shutoff criterion codeSignificanceCause of trouble/fault remedy
1...49* → AnchorCompressor off
t  Electrical system voltage is or has been less than 9.5 V with engine running
t  Voltage dips in power supply to operating and display unit, Climatronic control unit -J255- or to control unit in dash panel insert -J285-
 10* → Anchor 
t  Electrical system voltage (at connector “D” contact “12”) too low or fault in earth connection to operating and display unit, Climatronic control unit -J255- → Chapter
–  Use current flow diagram to check power supply
–  Fault rectification → Chapter and Electrical checks → Chapter

  Note
Depending on the version of the operating and display unit, Climatronic control unit -J255-, code “9” or “10” is displayed for this compressor shutoff criterion if the electrical system voltage is too low.
   
Display zoneCompressor shutoff criterion codeSignificanceCause of trouble/fault remedy
1...411* → AnchorCompressor off
t  Engine temperature too high
t  The control unit in dash panel insert -J285- has detected an excessively high engine temperature (coolant temperature greater than 118 °C) and transmitted this via the convenience data bus system to the operating and display unit, Climatronic control unit -J255- → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051 and → Electrical system; Rep. Gr. 90
 12* → AnchorCompressor off
t  Air conditioner compressor shutoff currently active (with display in zone “1”)
t  Air conditioner compressor shutoff was active for more than 12 seconds (with display in zones “2”, “3” or “4”)
t  The engine control unit has switched off the air conditioner compressor for a brief period (e.g. on vehicle acceleration)
t  The engine control unit has switched off the air conditioner compressor on account of a fault.
–  Interrogate fault memory of engine control unit → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051, → Ignition and injection system; Rep. Gr.01 or → Diesel glow plug and injection system; Rep. Gr.01
 13Not used at present 

   
Display zoneCompressor shutoff criterion codeSignificanceCause of trouble/fault remedy
1...414* → AnchorCompressor off
t  In the course of the current driving cycle, the high-pressure sender -G65- has supplied a pressure signal with a ratio greater than 87.5% (pressure too high) at least 30 times.
t  Loose contact in power supply or earth connection to high-pressure sender -G65-
t  Loose contact in wiring between high-pressure sender -G65- and operating and display unit, Climatronic control unit -J255-
t  Fault at high-pressure sender -G65- or in refrigerant circuit
t  Problem with actuation of radiator fan(s) -V7-
–  Fault table, → Chapter and Electrical checks → Chapter
 15Compressor off
t  The temperature measured by the evaporator outflow temperature sender -G263- is less than 2 °C (only displayed in zone “1”)
t  The air temperature in the area of the evaporator is less than 2 °C
–  Check measured value of evaporator outflow temperature sender -G263- (display group “007”) → Chapter,
–  If the sender measured value is OK and the temperature drops below 2 °C with the compressor in operation, check actuation of air conditioning system compressor regulating valve -N280- → Chapter (final control diagnosis) and Electrical checks → Chapter.
–  If actuation of the air conditioning system compressor regulating valve -N280- is OK, there is a fault in the refrigerant circuit (this can only be located and eliminated at a specialist air conditioner workshop). → Air conditioner with refrigerant R134a

   

Display group "003” > < Display group "002”