| Possible cause of odour formation at the air conditioner |
| Air conditioner odours may have different causes. Only some of these odours occur in the evaporator of the air conditioning unit and can therefore be eliminated by cleaning the evaporator. |
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| Generally occurs in the engine compartment due to leakage at the engine or gearbox |
| Sulphur-like smell of exhaust gas |
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| Caused by leakage at the exhaust system |
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| Caused by exhaust gas ingressing into the passenger compartment e.g. on reversing (on driving through a cloud of exhaust fumes). |
Note | If the fishy odour occurs in both fresh-air and air recirculation mode, check the heat exchanger of the air conditioning unit for leaks. |
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| Caused by leakage at engine cooling system or air conditioner heat exchanger |
| Odour given off by floor coverings, retrofitted loose seat covers, etc. |
| Mouldy smell from front end of vehicle |
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| Caused by water flowing into the fresh air intake housing of the air conditioning unit if the plenum chamber cover is damaged or not correctly fitted → Chapter. |
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| Caused by accumulation and deposits of foreign matter such as leaves, pine needles etc. |
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| Caused by water not being able to drain out of the plenum chamber; check plenum chamber water drains → Chapter. |
| Odour from air conditioning unit |
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| Odours originating in the air conditioning unit are usually perceptible in both fresh air mode and air recirculation mode. If an odour problem occurs only in fresh air mode or only in air recirculation mode, the air conditioning unit is not normally the cause of the problem. |
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| If a heat exchanger is leaking, the odour of the escaping coolant will be perceptible in both fresh-air and air recirculation mode (constant flow of air through the heat exchanger). |
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| Caused by too much condensation in the air conditioning unit; check condensation drain → Chapter. |
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| Caused by old or severely contaminated dust and pollen filters; check dust and pollen filter → Chapter |
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| Caused by deposits on evaporator fins; use ultrasonic A/C cleaner -VAS 6189A- to clean evaporator → Chapter |
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