Determining Malfunction If Deviation From Specified Value

The required cooling output is not attained. Refer to COOLING OUTPUT, CHECKING  and COOLING OUTPUT, CHECKING .

If a target value is not reached, this can be caused by various things:

-- Determine the cause. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding"  function.

Possible causes for the deviation of the target value:

• Dirty radiator or A/C system condenser.
• Retrofitted components at or in the front end.
• Fault in the activation or function of the Coolant Fan -V7- /Coolant Fan 2 -V177-.
• Fault in the coolant circuit, the coolant gets too hot.
• Fault in the activation of the A/C Compressor Regulator Valve -N280- by the A/C Control Module -J301- /Climatronic Control Module -J255- (vehicles without a high voltage system).
• A request transmitted by other control modules to the A/C Control Module -J301- /Climatronic Control Module -J255- to switch off the A/C Compressor Regulator Valve -N280- actuation (vehicles without a high voltage system).
• Fault in the A/C Compressor Regulator Valve -N280- function (vehicles without a high voltage system).
• Fault in the refrigerant circuit or A/C compressor.
• Fault in the activation or the function of the Battery Regulation Control Module -J840-, the Electrical A/C Compressor -V470-, the A/C Compressor Control Module -J842- or the Heater and A/C Unit Refrigerant Cut-Off Valve -N541-

If a fault was detected in the refrigerant circuit by the"Guided Fault Finding"  :

-- If there is a fault in the refrigerant circuit the necessary work may only be performed by qualified personnel. If this is not possible, bring the vehicle to a workshop that has the necessary tools and in which the work can be performed accordingly by qualified personnel. Refer to A/C SYSTEM, GENERAL INFORMATION (R134a) or LAWS AND REGULATIONS (R1234yf) . Bring the detected problems to the attention of the workshop.