Possible Concerns

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NOTE:

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 REFRIGERANT CIRCUIT - 1 , REFRIGERANT CIRCUIT - 2 , REFRIGERANT CIRCUIT 1234yf - 2 , REFRIGERANT CIRCUIT GENERAL INFORMATION R134a , REFRIGERANT CIRCUIT R134a .

-- Check the routing of the refrigerant lines they must not contact other components and must be installed without tension (adjust if necessary). Refer to REFRIGERANT CIRCUIT - 1 , REFRIGERANT CIRCUIT - 2 , REFRIGERANT CIRCUIT 1234yf - 2 , REFRIGERANT CIRCUIT GENERAL INFORMATION R134a , REFRIGERANT CIRCUIT R134a .

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 .

NOTE:

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 CONDENSATION WATER DRAIN, REMOVING AND INSTALLING / 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 CONDENSATION WATER DRAIN, REMOVING AND INSTALLING / 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 PLENUM CHAMBER WATER DRAIN, CHECKING , PLENUM CHAMBER COVER, REMOVING AND INSTALLING .

-- Check the plenum chamber water drains they must not be closed (for example by leaves). Refer to PLENUM CHAMBER WATER DRAIN, CHECKING , OVERVIEW - A/C SYSTEM [COMPONENT LOCATION] .

NOTE:

Component Location And Additional For These Components. Refer To OVERVIEW - A/C SYSTEM [COMPONENT LOCATION] / OVERVIEW - BULKHEAD .