Evaporator Case: Service and Repair

Cleaning Front and Rear A/C System Evaporator

Special tools, testers and auxiliary items required

• Ultrasound A/C Cleaner (VAS 6189).

• Cleaning Fluid (VAS 6189/1)

• Numerous procedures varying in their application and effect are available on the market for cleaning the evaporator. Currently Audi offers the Ultrasound A/C Cleaner (VAS 6189) which has been approved and released for cleaning the evaporator.

• Odors from the air conditioning system can be caused by various things, only a portion of these orders come from the evaporator and can be corrected by cleaning it with the Ultrasound A/C Cleaner (VAS 6189).

• Causes of Odor, refer to => [ Causes of Odor ] Symptom Related Diagnostic Procedures.

• The evaporator in the rear A/C unit can currently be cleaned in the installed state only with the Ultrasound A/C Cleaner (VAS 6189). The evaporator is installed under the center console and is only accessible after removal of various components => [ Rear Fresh Air Blower (V80) ] Description and Operation. In this vehicle, the air escaping from the rear A/C unit is drawn in either by the front A/C unit or under the center console depending on the setting on the Climatronic Control Module (J255) , the Rear A/C Display Control Head (E265) and the prevailing environmental conditions. The air coming from the front A/C unit is first routed through the dust and pollen filter and the evaporator in the front A/C unit. Since the dust particles in the air are filtered out here, these cannot reach the evaporator in the rear A/C unit.

• In the event of a complaint due to an odor from the rear A/C unit, the evaporator in the rear A/C unit can currently be cleaned in the installed state without removing various components only using the Ultrasound A/C Cleaner (VAS 6189).

• To clean the evaporator in the rear A/C unit with the Ultrasound A/C Cleaner (VAS 6189) , set the air distribution on the front A/C unit so that the major part of the air is routed to the rear A/C unit, and clean the evaporator in the same way as described for the front evaporator (in recirculation mode the air and vaporous cleaning fluid are drawn in at the front and routed to the rear A/C unit).

• In recirculation mode, the Rear Fresh Air Blower (V80) installed in the rear A/C unit draws in air under the center console in the area of the front seats. If odors occur in the A/C unit, check the center console and the area under the front seats for moisture and contamination. Check the condensation water drains in the rear A/C unit for blockage and the heater core installed in the rear A/C unit for leaks, refer to => [ Rear Condensation Water Drains, Checking ] Rear Condensation Water Drains, Checking and => [ Components of Rear A/C Unit Overview ] Components of Rear A/C Unit Overview.

Preparation

- Check whether the odor is actually in the evaporator of the front A/C unit by switching from fresh air to recirculation mode.

• The odor can only be removed by cleaning with the Ultrasound A/C Cleaner (VAS 6189) if it originates in the evaporator.

- Check the plenum chamber and the water drain valves for dirt and debris and clean if necessary. Refer to => [ Plenum Chamber Water Drain ] Service and Repair.

- Remove the dust and pollen filter and check for odors and dirt, refer to => [ Dust and Pollen Filter ] Service and Repair.

• On this vehicle, the dust and pollen filter is installed between Fresh Air Blower (V2) and evaporator, therefore it must be removed for the cleaning.

- Clean the installation compartment of the A/C dust and pollen filter (remove leaves, dust and other contaminants). Refer to => [ Dust and Pollen Filter ] Service and Repair.

- Reseal opening on A/C unit through which dust and pollen filter was removed.

- Start engine.

- On the Climatronic control module, set the recirculation mode and switch off the A/C compressor (the indicator lamp in the AC button does not illuminate).

- Open the instrument panel vents and the vents in the rear center console.

- On the Climatronic control module, (and if present also on the rear A/C display control head), set the lowest possible temperature (cold temperature setting).

- Closes the windows and sunroof.

- On the Climatronic control module, (and if present also on the rear A/C display control head), set the lowest fresh air blower speed and select the flow direction to the instrument panel vents (the vent in the rear center console).

- On the Climatronic control module, select the air flow direction to the instrument panel vents.

- If present, on the rear A/C display control head, select the air flow direction to the vents in the rear center console.

Cleaning

- Shake the bottle of Cleaning Fluid (VAS 6189/1) and pour the contents into the Ultrasound A/C Cleaner (VAS 6189) (when doing this, be sure to read the operation manual which comes with the Ultrasound A/C Cleaner (VAS 6189) ).

- Place the Ultrasound A/C Cleaner (VAS 6189) in the passenger's footwell.

- Start the Ultrasound A/C Cleaner (VAS 6189) (according to Operating instructions) and route the outlet hose belonging to it so that vapor escaping via the front A/C unit recirculation opening (in the passenger footwell behind the glove compartment) is drawn in by the fresh air blower (V2).

• Via the air ducts between the front A/C unit and the air distributor housing/rear A/C unit, part of the cleaning fluid is also drawn in by the rear fresh air blower (V80) and routed through the components in the air distributor housing/rear A/C unit.

- Close the vehicle doors.

• The cleaning process takes about 15 to 20 minutes. It is complete when vapor no longer comes out of outlet hose.

Finishing steps

- Switch off the Ultrasound A/C Cleaner (VAS 6189).

- Open the vehicle doors and air out the passenger compartment for at least 10 minutes.

- Remove Ultrasound A/C Cleaner (VAS 6189) from vehicle and clean it according to operating instructions.

- Switch off ignition.

- Install the dust and pollen filter, refer to => [ Dust and Pollen Filter ] Service and Repair.