Note.
- For vehicles where it is not possible to connect adapters to the refrigerant pipes, use eg an air gun with a rubber nozzle to purge individual components. In this case, you must be very careful not to damage (do not deform or scratch) fittings.
- The evaporator, with the expansion valve or restrictor removed, must be purged through the low pressure connection (large diameter).
- The units must only be blown against the direction of the refrigerant flow.
- Check expansion valve, replace if dirty or corroded.
- If there are dark sticky deposits in the nodes that cannot be removed with compressed air, these nodes must be replaced.
- A thin light gray coating on the inner walls of the 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 mounted dryer, the drying cartridge or dryer must be replaced.
Possible malfunctions of the refrigerant circuit
Note.
- The air-conditioning system is working correctly if the front panel vents are venting air at a temperature of 7°C or lower.
- Setting up the Chmatronic system: "LO".
- Air conditioning setting: "AU" ON; "max"; "kalt".
Verification conditions
During the self-diagnosis of the air conditioner using the tester -VAS 5051 A- in the "Guided Fault Finding" no faults detected, compressor shutdown conditions are not displayed in the measured value block (only on vehicles with self-diagnosis "air conditioner").
Possible malfunctions
Note.
- Complete lack of cooling. Insufficient cooling efficiency at any vehicle speed or at any engine speed.
- No cooling or insufficient cooling after several kilometers of travel.
- The air conditioner compressor, its solenoid clutch -N25- or its control valve N280 are switched off by the signal from the minimum pressure sender -F73-, the maximum pressure sender for the solenoid clutch -F118-, the air conditioner pressure switch -F129- or a signal from the control and display unit Climatronic -E87- or 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 occur:
Noise from air conditioner compressor
Tighten the screws securing the air conditioner compressor and its bracket with a torque wrench.
Check the laying of the refrigerant pipelines: they must not touch other components and have mechanical stresses (align if necessary).
Immediately after turning on the air conditioner and / or when cornering or when braking, noise occurs (refrigerant hydraulic shocks):
Empty, evacuate and refill the refrigerant circuit (too much refrigerant in the circuit).
Note. The cause of this malfunction may also be an excess of refrigerant oil in the circuit (e.g. when the compressor was replaced, the oil quantity was not corrected). 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 screw plug). To facilitate this operation, you must manually turn the pulley or electromagnetic clutch of the compressor. After that, the entire refrigerant oil charge must be introduced into the refrigerant circuit according to the workshop manual for the respective vehicle (straight to the compressor - 50 grams).
The climate system works normally, but water is sprayed from the deflectors (on the front or in the footwell)
Check that the drain hose is laid correctly: it must not be pinched or kinked.
Check the drain hose valve: it must not be sealed with wax or underbody protection and must open and close freely.
Check the plenum box cover: it must not be damaged and must be correctly installed (water must not flow into the evaporator).
Check the drains of the plenum box: they must not be blocked (like leaves).
Odors from the heater and air conditioner module
Does the smell come from the evaporator or from the heat exchanger?
fishy smell
Due to a leak in the engine cooling system or in the heat exchanger of the heater and air conditioner module.
Note. If the fishy smell fades as the temperature is adjusted "kalt" (cold) and amplifies when tuned "warm'' (warm), check the tightness of the heat exchanger.
Smell «burnt» clutch
Vapors from carpets, non-standard seat covers, etc.
Smell of rot and mildew
Due to the accumulation and deposits of foliage, needles, etc. in the drainage box.
Note. Clean the water box.
Because of the water not flowing out of the plenum box.
Note: Check the drains of the plenum box.
Smell from the heater and air conditioner module
Note. Odors that may appear in the heater and air conditioner module are felt both in fresh air mode and in recirculation mode.
Due to excess condensation in the heater and air conditioning module.
Note. Check drain hose.
Due to an old or heavily contaminated cabin filter.
Note. Check cabin filter.
Due to deposits on the evaporator plates
Note. Clean evaporator with ultrasonic cleaner -VAS 6189A-.