Heating & Air Conditioning: Maintenance Audi TT 8N facelift

Evaporator housing drain valve, checking, removing and installing

Checking

Scheme 13

1. Ensure that flap on valve -A- is not damaged, obstructed and is able to close freely. The flap opening must face downwards.

Removing and installing

1. Fold back pre-punched flap -D- in insulation mat and remove valve.

Note. Remove valve -A- downwards from floor. When installing, make sure it is correctly positioned in bulkhead -B-. When installed, the valve must not touch flap -D- in insulation mat. The valve must not be sprayed with rustproofing wax or undercoating material. If customer complaints mention dampness in the passenger compartment, ensure duct -C- is correctly positioned in valve -A-. Two installed versions of valve are possible: version -1- through m.y. 2000 and version -2- (with two lower openings) installed as a running change from m.y. 2001.

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 expansion valve.
4. Always flush components in opposite direction of refrigerant flow.

1. Flush evaporator through the low pressure line with the high pressure line removed.
2. Blow through the refrigerant line from receiver drier to compressor in flow direction of refrigerant (there is no thread on connection to compressor).
3. If any component has dark thick deposits that cannot be removed with compressed air, replace component.
4. Thin light gray deposits in refrigerant lines and hoses are normal and do not impair the function of the system.

1. Always replace receiver drier 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).

1. System is unable to pull a constant vacuum during evacuation of a leak-free system due to excessive moisture in the system.
2. Refrigerant system has been open longer than the time required for normal repairs (i.e. following an accident).
3. Based on temperature and pressure measurements, the system is diagnosed with moisture contamination.
4. Compressor is replaced due to noises or internal damage.

1. Flushing is required after replacing certain components in certain situations, see A/C refrigerant system, replacing components. Refer to «A/C refrigerant system, replacing components»(ref-276291-S19715115502008010300000) .