Odors In Vehicles With A/C System Information

Odors from the A/C system can come from various sources. Only a portion of these odors come from the heater and 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
Sulfurous 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	Leak in the cooling system of engine or of A/C system heater core. -- If the fishy odor is also detected in fresh air mode as well as in recirculating air mode, check the front and rear 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. Dirt or moisture in the front passenger footwell or under the front seats -- Check the front passenger footwell for moisture, dry and 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 of the heater and A/C unit. Refer to CONDENSATION WATER DRAIN, REMOVING AND INSTALLING . 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 slats -- Clean the evaporator. Refer to EVAPORATOR, CLEANING .