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Home >> Audi >> 2017 >> A6 Quattro Competition >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> General Servicing >> Climate Control System (Precautions & General Information - CAEB, CGXB, CEUC, CTUA, CEUC, CAED, CHJA, CPNB, CRDB, CPNB, CREC, CTGE, CYNB, CWUC, CREH, CWUB) >> 00 General, Technical Data >> General Information >> Odors In Vehicles With A/C System

Odors In Vehicles With A/C System

Odors from the Air Conditioning (A/C) system can come from various sources. Only a portion of these odors come from the A/C unit evaporator and can be corrected by cleaning the evaporator.

Odor Type Possible Causes and Solution
Smells like burnt oil
  • Mostly forms in the engine compartment due to leaks on the engine or transmission
-- Eliminate the leaks on the engine or transmission
Sulphurous smell similar to exhaust
  • Leak in the exhaust system
  • Exhaust fumes, which get into the passenger compartment, for example, when driving in reverse through an exhaust gas cloud
-- Eliminate the leaks in the exhaust system
Fishy smell like coolant
  • Leak in the cooling system of engine or of A/C system heater core.
-- If the fishy odor is detected also in recirculated air mode as well as in fresh air mode, check the A/C system heater core for proper seal.
Smells like a burned clutch.
  • Coupling plates are worn or there is an operating error
-- Check the coupling
Evaporation
  • Floor mats, retroactively installed decorative seat covers, etc.
-- Check the floor mats or decorative seat covers. Replace or clean.
Rotten, mildewy, moldy or musty smell from the front of the vehicle
  • If the plenum chamber cover is damaged or incorrectly installed, water can enter the fresh air intake via the water channel where applicable.
-- Check the fresh air intake for the A/C unit. Refer to FRESH AIR INTAKE, REMOVING AND INSTALLING .
  • Contaminants, such as leaves, pine needles, etc. collecting in the plenum chamber
-- Check the plenum chamber for contaminants. Refer to PLENUM CHAMBER WATER DRAIN, CHECKING .
  • Water that cannot drain out of the plenum chamber
-- Check the water drains. Refer to PLENUM CHAMBER WATER DRAIN, CHECKING .
Smell from the A/C unit.
  • Too much condensation water in A/C unit
-- Check the condensation water drain. Refer to CONDENSATION WATER DRAIN, CHECKING .
  • Old or heavily contaminated dust and pollen filter.
-- Check the dust and pollen filter. Refer to DUST AND POLLEN FILTER, REMOVING AND INSTALLING .
  • Deposits on evaporator fins
-- Clean the evaporator. Refer to EVAPORATOR, CLEANING .
NOTE:

The odor can only be removed by cleaning with the Ultrasound A/C Cleaner :VAS6189B  if it originates in the evaporator.

Numerous procedures varying in their application and effect are available on the market for cleaning the evaporator. At this time Audi has tested and approved cleaning the evaporator using the Ultrasound A/C Cleaner :VAS6189B  or a Suction Feed Spray Gun :VAG1538  , for example. Additional procedures tested and approved by Audi.

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