Possible Concerns
With all complaints marked with *. Refer to PRESSURES, CHECKING .
If a malfunction occurs at only one evaporator in vehicles with two evaporators, also check the pressures in the refrigerant circuit. Refer to PRESSURES, CHECKING .
- Total cooling system failure.*
- Insufficient cooling output at all vehicles speeds or engine speeds.*
- None or insufficient cooling after driving a few miles. *
- No cooling or insufficient cooling at one or both evaporator(s) (on vehicles with two heater and A/C units/evaporators).*
- The activation of the A/C compressor (via the A/C Clutch -N25- or the A/C Compressor Regulator Valve -N280-) is switched off by the corresponding control module (for example the Front A/C Display Control Head -E87-, the A/C Control Module -J301- or the Climatronic Control Module -J255-) due to high or too low refrigerant circuit pressure*. Use the Vehicle Diagnostic Tester in the A/C system"Guided Fault Finding" function.
- The Electrical A/C Compressor -V470- is activated by the A/C Compressor Control Module -J842- due to too high or too low pressure*. Use the Vehicle Diagnostic Tester in the A/C system"Guided Fault Finding" function and the battery regulation.
- No or sharp decrease in fresh-air supply after driving several miles (evaporator iced up). * Use the Vehicle Diagnostic Tester in the A/C system"Guided Fault Finding" function.
From These, the Following Complaints May Also Occur:
The A/C compressor makes noises
-- Tighten compressor securing bolts and compressor bracket using a torque wrench. Refer to SYSTEM OVERVIEW - REFRIGERANT CIRCUIT .
-- Check the routing of the refrigerant lines they must not contact other components and must be installed without tension (adjust if necessary). Refer to SYSTEM OVERVIEW - REFRIGERANT CIRCUIT .
Noise (refrigerant hammer) occurring immediately after switching on air conditioner and/or when cornering or braking:
-- Discharge, evacuate and charge refrigerant circuit (too much refrigerant or refrigerant oil in the circuit). Refer to WORKING WITH A/C SERVICE STATION and PRESSURES, CHECKING .
Too much refrigerant oil in the circuit could also cause this problem. This could occur if the amount of refrigerant oil was not adjusted when replacing the A/C compressor. Refer to COMPONENTS, REPLACING .
Water sprays out of vents (in dash panel or footwell) although air conditioning system is otherwise functioning properly:
-- Check the condensation water drain is routed properly it must not be crushed or kinked. Refer to Front Heater and A/C Unit .
-- Check condensation drain valve, it must not be clogged by wax or underbody sealant and must close properly. Refer to Front Heater and A/C Unit .
-- Check the plenum chamber cover, it must not be damaged and must be properly installed (no water may enter the evaporator). Refer to COMPONENT LOCATION OVERVIEW - COMPONENTS OUTSIDE OF VEHICLE INTERIOR .
-- Check the plenum chamber water drains, they must not be closed (for example due to leaves). Refer to COMPONENT LOCATION OVERVIEW - COMPONENTS OUTSIDE OF VEHICLE INTERIOR .
Component location and additional for these components. Refer to Component Location Overview - A/C System .