Odors In Vehicles Without A/C System

Odors from the heater can come from various sources. Only a portion of these orders come from the heater.

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 cooling system of the engine or of the heater core for the heater -- If the fishy odor is detected also in recirculating air mode as well as in fresh air mode, check the heater core for the heater 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 heater fresh air intake. 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 .
Odors from the heater	Odors originating in the heater can mainly be detected in fresh air mode and recirculating air mode. If an odor occurs only in fresh air or recirculation mode, the cause is usually not the heater. When the heater core is leaking, the odor of the escaping coolant can be detected in fresh air mode and in recirculating air mode. The odor can be less noticeable in the "cold" setting on the Heater Control Module -J65- than in heating mode. Reason: Air does not flow constantly through the heater core. However, coolant does flow constantly through the heater core. 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 .

The evaporator is not used on vehicles without an A/C system. Deposits on the slats of the evaporator can under certain climatic conditions can still lead to odor.