Conditions

No A/C

Fault symptoms
No A/C

Diagnostic help
Deals with conditions for A/C ON.

If the A/C clutch engages, see "No/inefficient cooling." No/Inefficient Cooling





Diagnostic procedure

1. Checking DICE programming
^ Contact DICE.

Is DICE programmed for A/C?
YES
^ Go to step 2.
NO
^ Go to step 19.

2. Select control system
^ Select the type of control system the car is equipped with.
MCC
^ Go to step 4.
ACC
^ Go to step 3.

3. Checking outside temperature
^ Check outside temperature.

Is the outside temperature above +5 degrees?
YES
^ Go to step 4.
NO
^ Go to step 7.





4. Checking compressor engagement from Trionic
^ Turn the ignition key to ON





^ Contact Trionic.





^ Activate: A/C relay (ON)
^ A/C clutch should engage

Is the function correct?
YES
^ Go to step 8.
NO
^ Go to step 5.





5. Checking the electromagnetic clutch
^ Unplug connector: A/C compressor clutch (170).





^ Connect a jumper lead between B+ and the A/C compressor connector, pin 1 (male connector).
^ A/C clutch should engage.

Is the function correct?
YES
^ Go to step 6.
NO
^ Replace: A/C compressor clutch.





6. Checking the power supply
^ Connect a test lamp between pin 1 on the A/C relay retainer (30) and a reliable ground.





^ The test lamp should light.

Is the function correct?
YES
^ Go to step 18.
NO
^ Rectify lead between fuse 14 in the main fuse box and pin 1 on the A/C relay retainer (30).





7. Checking outside temperature (cont.)
^ Park the car in a garage where the outside temperature is above +5 degrees C.
^ Turn the ignition key to ON.





^ Contact the ACC.





^ Activate : Outside temperature 20 °C (ON).
^ Activate: A/C relay (ON).
^ A/C clutch should engage.

Is the function correct?
YES
^ Go to step 8.
NO
^ Go to step 16.





8. Checking A/C In in DICE
^ Start the engine and run it at idling speed.





^ Press the A/C button, select maximum cold and fan on.





^ Contact DICE.
^ Read value: A/C In (Bus from ACC).
^ The diagnostic tool should show: ON.

Is the function correct?
YES
^ Go to step 9.
NO
^ Replace: ACC/MCC unit.

9. Checking A/C pressure, read in DICE
^ Read: A/C Pressure (DICE).
^ Which value is shown on the diagnostic tool?

LESS THAN 2 BAR
^ Go to step 1O
MORE THAN 27 BAR
^ Go to step 1O
2 TO 27 BAR
^ Go to step 11.





10. Checking the pressure sensor
^ Connect the pressure gauge stand.
^ Contact DICE
^ Read: A/C Pressure (DICE).
^ The value shown on the pressure gauge for the high-pressure side should correspond to the value for the pressure sensor.

Is the function correct?
YES
^ Rectify leak and fill the system with correct amount of refrigerant.
NO
^ Replace: Pressure sensor A/C.

11. Checking coolant temperature, read in DICE
^ Read: Coolant temperature (Bus from Trionic) (DICE).

Is the engine temperature, read in DICE, above +125 degrees?
YES
^ Go to step 12.
NO
^ Go to step 13.

12. Checking engine temperature
^ Check if the engine temperature seems to be reasonable compared to the value shown on the diagnostic tool.

Is the engine temperature reasonable?
YES
NO
^ Rectify the fault.

13. Checking evaporator temperature in DICE
^ Read: Evaporator temperature (DICE).

Is the evaporator temperature, read in DICE, below +5 °C (41 °F)?
YES
^ Check that the evaporator temperature seems reasonable.
NO
^ Go to step 14.





14. Checking A/C In in Trionic
^ Contact Trionic.





^ Read value: A/C In.
^ The diagnostic tool should show: ON.

Is the function correct?
YES
^ (Trionic T7) Before Changing a Control Module
^ Go to step 15.
NO
^ (DICE) Before Changing a Control Module

^ Go to step 15.





15. Final check
^ Delete diagnostic trouble codes in all Systems.





^ Perform a driving cycle:
^ Drive the car with varying engine loads and at varying engine speeds for five minutes.
^ Evaluate the driving cycle:
^ Check that the malfunction does not persist after the driving cycle.

Is the function correct?
YES
^ The steps taken to rectify the fault were correct.
NO
^ Before Changing a Control Module





16. Checking the electromagnetic clutch
^ Unplug connector: A/C compressor clutch (170).





^ Connect a jumper lead between B+ and the A/C compressor connector, pin 1 (male connector).
^ A/C clutch should engage

Is the function correct?
YES
^ Go to step 17.
NO
^ Replace: A/C compressor clutch.





17. Check the power supply
^ Connect a test lamp between pin 1 on the A/C relay retainer (30) and a reliable ground.





^ The test lamp should light.

Is the function correct?
YES
^ Go to step 18.
NO
^ Rectify lead between fuse 14 in the main fuse box and pin 1 on the A/C relay retainer (30).





18. Checking lead to A/C compressor
^ Connect a jumper lead between pin 1 (30) and pin 2 (87) on the relay retainer.





^ Connect a test lamp between pin 1 on the female connector of the A/C compressor clutch and a reliable ground.





^ The test lamp should light.

Is the function correct?
YES
^ Replace : A/C compressor relay
NO
^ Rectify lead between pin 2 on the relay retainer and pin 1 on the A/C compressor.





19. Programming the DICE
^ Programme DICE for A/C.





^ Delete diagnostic trouble codes in all systems.
^ Carry out a function check.

Is the function correct?
YES
^ The steps taken to rectify the fault were correct.
NO
^ Before Changing a Control Module