Why Does the Air from the Car Air Conditioner Smell Like Engine Oil?
2 Answers
Car air conditioner blowing air with an engine oil smell may be due to engine oil leakage or driving with the external circulation mode on. Here are the detailed reasons: 1. Some car models have their air conditioning air doors installed in the engine compartment: This means that part of the air comes from the engine compartment. When there is engine oil leakage or seepage, the warm air may carry an engine oil smell. 2. If the external circulation mode is turned on while driving: The smell of engine oil from the engine compartment can enter the cabin through the external circulation ducts. Additionally, if the replaced cabin air filter has traces of engine oil, the warm air blown out may also carry an engine oil smell.
If there's an oily smell coming from the car's air conditioning vents, it's most likely due to oil leaks in the engine compartment being drawn in. For example, when the crankcase ventilation system fails, oil vapor escapes, and since the AC intake is nearby, using the external air circulation can easily draw in those odors. If the evaporator gets contaminated with oil, it can also release an engine oil smell during cooling. Common causes include aging seals or loose screws leading to oil seepage. I recommend regularly cleaning the engine compartment and checking the oil pan and transmission seals. Don't ignore this issue—such odors indicate internal vehicle deterioration. Long-term neglect can increase repair costs and safety hazards. In severe cases, oil dripping onto the hot exhaust pipe could evaporate and potentially cause a fire risk.
