Note.
- For vehicles where adapters cannot be connected to the refrigerant pipes, use, for example, a pneumatic gun with a rubber nozzle to blow out individual components. In this case, you must act very carefully so as not to damage (do not deform or scratch) nipples.
- The evaporator should be purged through the low pressure pipe fitting with the expansion valve or throttle removed (large diameter).
- Blow through the units only against the direction of the refrigerant flow.
- Check the expansion valve, replace if dirty or corroded.
- If there are dark sticky deposits in the units that cannot be removed with compressed air, these units must be replaced.
- A thin light-grey coating on the inner walls of refrigerant pipelines does not affect the performance of the units.
- After purging, be sure to replace the receiver/receiver-collector and throttle. For condensers with a hang-on dehydrator, it is necessary to replace the dehydrator cartridge or dehydrator.
Possible faults in the refrigerant circuit
Note.
- The air conditioning system is operating correctly if the air coming out of the front panel vents is at a temperature of 7°C or lower.
- Chmatronic system setting: "LO".
- Setting the air conditioning system: "AC" ON; "max"; "kalt".
Verification conditions
During self-diagnosis of the air conditioning system using the VAS 5051 A tester in the Guided Fault Finding mode, no faults were detected; the conditions for shutting off the compressor are not displayed in the block of measured values (only on vehicles with self-diagnosis of the air conditioning system).
Possible malfunctions
Note.
- Complete lack of cooling. Insufficient cooling efficiency at any vehicle speed or engine speed.
- No cooling or insufficient cooling after several kilometers of driving.
- The air conditioning compressor, its electromagnetic clutch "N₂5" or its regulating valve N₂80 are switched off by a signal from the minimum pressure sensor "F73", the maximum pressure sensor for the electromagnetic clutch "F118", the air conditioning pressure switch "F129" or by a signal from the Climatronic control and display panel "E87" or the Climatronic control unit "J255" due to too high or too low pressure.
No or noticeable reduction in fresh air supply after several kilometers of travel (evaporator icing).
In addition, the following malfunctions may also occur:
Noise from the air conditioning compressor
Tighten the air conditioning compressor mounting bolts and its bracket using a torque wrench.
Check the refrigerant pipelines: they should not touch other components and have mechanical stress (align if necessary).
Immediately after turning on the air conditioning system and/or when turning or braking, noise appears (refrigerant hydraulic shocks):
Empty, evacuate and recharge the refrigerant circuit (too much refrigerant in the circuit).
Note: This malfunction may also be caused by excess refrigeration oil in the circuit (for example, when replacing the compressor, the amount of oil was not adjusted). In this case, the circulation circuit must be flushed with R134a refrigerant. The refrigerant must be drained from the compressor through the drain hole (replace the sealing ring of the threaded plug). To facilitate this operation, manually turn the pulley or electromagnetic clutch of the compressor. After that, you need to introduce into the refrigerant circulation circuit the entire filling volume of refrigeration oil according to the repair manual for the corresponding car (directly into the compressor - 50 grams).
The climate control system works fine, but water sprays from the vents (on the dashboard or in the footwell)
Check that the drainage hose is laid correctly: it should not be pinched or kinked.
Check the drain hose valve: it should not be covered with wax or underbody coating and should open and close freely.
Check the casing of the water drainage box: it should not be damaged and should be installed correctly (water should not flow into the evaporator).
Check the drainpipes of the water drainage box: they should not be blocked (for example, foliage).
Odors from the heater and air conditioning module
Is the smell coming from the evaporator or the heat exchanger?
Fishy smell
Due to a leak in the engine cooling system or in the heat exchanger of the heater and air conditioning module.
Note: If the fishy smell decreases with the "kalt" (cold) temperature setting and increases with the "warm" (warm) setting, check the heat exchanger for leaks.
The smell of a "burnt" clutch
Fumes from carpets, non-standard seat covers, etc.
The smell of rot and mold
Due to accumulation and deposits of leaves, needles, etc. in the drainage box.
Note: Clean the water drainage box.
Because of water not flowing out of the drainage box.
Note: Check the gutters of the water drainage box.
Smell from the heater and air conditioning module
Note: Odors that may appear in the heating and air conditioning module are felt both in the supply ventilation mode and in the recirculation mode.
Due to excess condensation in the heating and air conditioning module.
Note: Check the drain hose.
Due to an old or heavily contaminated cabin filter.
Note: Check the cabin filter.
Due to deposits on the evaporator plates
Note: Clean the evaporator using the ultrasonic device "VAS 6189A".