Information On Odors In Vehicles With A/C System

WARNING: This page is about a different variant/trim than selected.

Odors from the 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 Corrective Measure
Smells like burnt oil	Usually originates 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 vehicle interior, for example, when driving in reverse through an exhaust gas cloud -- Eliminate the leaks in the exhaust system
Fishy smell like coolant	Leaks in the cooling system for the engine or for the heater core in the heater and A/C unit. -- If the fishy odor is also detected in recirculating air mode as well as in fresh air mode, check the heater and A/C unit heater core for leaks.
Smells like a burned clutch	Clutch plates are worn or there is an operating error -- Check the clutch
Evaporation	Floor mats, retroactively installed decorative seat covers, etc. -- Check the floor mats or decorative seat covers. Replace or clean.
Rotten, 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 rain water drain channel. -- Check the fresh air intake of the heater and 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 .
Odor from the heater and A/C unit	Too much condensation water in the heater and A/C unit -- Check the condensation water drain. Refer to CONDENSATION WATER DRAIN HOSE, 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:

Only if the odor originates in the evaporator can it be eliminated by cleaning with the Ultrasound A/C Cleaner :VAS6189B or with a Suction Feed Spray Gun :VAG1538 .

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 as well as corresponding information about them can be found, for example, in "Audi Dealer Portal" or in "Audi ServiceNet" (→ table).

The procedures listed below show how to access the "Audi ServiceNet". Depending on the country, the "Cleaning the A/C system" option can be found, for example, in the submenu "Original Parts". Follow the directions in the "Audi Partner Portal" or in "Audi ServiceNet" to find the direct path to the "Cleaning the A/C system" instructions.

Refer to EVAPORATOR, CLEANING