Air Conditioning: Maintenance Audi A6 C5 facelift

Evaporator housing drain valve, checking, removing and installing

1. Evaporator housing drain valve -A- must not be clogged and must close freely. The drainage hole must be at the bottom.

Scheme 10

Note. Remove evaporator housing drain valve from floor panel -B- in downward direction. When installed, the evaporator housing drain valve must not be touching the heat shield. The evaporator drain valve must not be clogged with wax or undercoating. When installing, position correctly in floor panel -B-. Drainage duct -A- is bolted to the floor panel with bolts -B- and must not interfere with the operation of the evaporator housing drain valve. see scheme 30 If the customer reports moisture in the vehicle interior, check and if necessary clean condensation drainage system and valve. Also check the operation of the two forced air extraction vents in the luggage compartment. See AIR EXTRACTION VENT, CHECKING. Foam sealing pad -A- must lie flush against the drainage duct. see scheme 31 The drainage duct and foam sealing pad can only be replaced when the air conditioner unit has been removed. See COMPLETE AIR CONDITIONER UNIT, REMOVING AND INSTALLING. The condensation drainage duct has a drip lobe -B- which prevents condensation on the duct from seeping back into the foam sealing pad. see scheme 31 If the drip lobe has broken off, install spout -A- (Part No. 8D0 860 155) as shown in illustration and seal it todrainage duct with silicone sealant adhesive.

1. If passenger compartment is moist: Check air extraction outlets in passenger compartment (via luggage compartment). See «AIR EXTRACTION VENT, CHECKING»(ref-196290-S41668721532005100800000) . For vehicles as of model year 2002, check the signal for detection of windshield wiper operation at A/C Control Head -E87-. See Read measuring value block, «DISPLAY GROUP 017: MEASURING VALUES FOR SUNLIGHT PHOTO SENSOR -G107-, SIGNAL FROM WINDSHIELD WIPER SWITCH FOR WASHER PUMP AND WINDSHIELD WIPER»(ref-196289-S34296178882006050900000) . Check dust and pollen filter for soiling and the cover for correct installation. See «DUST AND POLLEN FILTER ELEMENT, REMOVING AND INSTALLING»(ref-196290-S35604089342005100800000) Check various positioning motors and the pertaining levers, pay particular attention to position of Air Flow Flap Motor -V71- and Recirculation Flap Motor -V113- and the pertaining flaps For vehicles as of model year 2002 and a compressor with A/C Compressor Regulator Valve -N280-, check measured value of Evaporator Vent Temperature Sensor -G263-. See Read measuring value blocks, «DISPLAY GROUP 010: MEASURING VALUES FOR EVAPORATOR VENT TEMPERATURE SENSOR -G263-, FRESH AIR INTAKE DUCT TEMPERATURE SENSOR -G89-, OUTSIDE AIR TEMPERATURE SENSOR -G17- AND CALCULATED OUTSIDE TEMPERATURE TRANSMITTED TO INSTRUMENT CLUSTER»(ref-196289-S23375464282006050900000) . If measured value of the sensor is too low under operating conditions specified by customer (at an ambient temperature above 0 ° C,colder than 0 ° C for a long period of time), observe notes for testing cooling performance. See «A/C SYSTEM COOLING PERFORMANCE, TESTING»(ref-196290-S30707258672005100800000) . In vehicles without Evaporator Vent Temperature Sensor -G263-, check vent temperature of air from evaporator e.g. via Sender for outlet temperature, floor outlet -G192- at the adjustment: "Temperature Lo" for driver's- and passenger side, 4 or 5 bars for fresh air blower RPM, air outlet in footwell and fresh air operation under operating conditions specified by customer. If measured value of the sensor is too low (at an ambient temperature above 0 ° C,colder than 0 ° C for a long period of time) observe notes for testing cooling performance. See «A/C SYSTEM COOLING PERFORMANCE, TESTING»(ref-196290-S30707258672005100800000) .

A/C refrigerant system (R-134a), flushing with compressed air and nitrogen

1. Use compressed air and nitrogen (available locally) to remove moisture, impurities and old refrigerant oil from A/C refrigerant system.
2. First blow out old refrigerant oil and dirt with compressed air, then dry components with nitrogen.
3. DO NOT blow compressed air and nitrogen through the compressor or restrictor.
4. Always flush components in opposite direction of refrigerant flow.
5. Flush evaporator through the low pressure line with the high pressure line removed.
6. Blow through the refrigerant line from accumulator to compressor in flow direction of refrigerant (there is no thread on connection to compressor).
7. If any component has dark thick deposits that cannot be removed with compressed air, replace component.
8. Thin light gray deposits in refrigerant lines and hoses are normal and do not impair the function of the system.
9. Always replace accumulator and restrictor after flushing.

Flush refrigerant system with compressed air and nitrogen if

1. Refrigerant oil is dark and viscous (thick).
2. Too much refrigerant oil is in the system following compressor replacement.
3. It is unclear or not known how much refrigerant oil is in system.
4. Moisture, dirt or other impurities have entered the refrigerant system (e.g. following an accident).
5. System is unable to pull a constant vacuum during evacuation of a leak-free system due to excessive moisture in the system.
6. Refrigerant system has been open longer than the time required for normal repairs (i.e. following an accident).
7. Based on temperature and pressure measurements, the system is diagnosed with moisture contamination.
8. Compressor is replaced due to noises or internal damage.
9. Flushing is required after replacing certain components in certain situations, see A/C refrigerant system, replacing components. See «A/C SYSTEM, REPLACING COMPONENTS»(ref-196290-S31858984402005100800000) .