Audi A3 - Poor performance of the air - conditioning system | HELLA
A3, from year 2003
All models with air conditioning
Poor performance of the air- conditioning system
If a customer complains about the above problem, this could be caused by a defective temperature sensor at the evaporator. The defective temperature sensor causes the evaporator surface to freeze so that heat exchange is no longer possible. First, a plausibility test should be performed using the diagnostic tester. Under the "Parameters" menu item, you can usually compare the temperatures of the interior temperature sensor and the sensor on the evaporator, when the air conditioning is switched off. If the measurement shows significant differences (interior 20 °C and e vaporator 30 °C), this is already an indication of a faulty t emperature sensor on the evaporator. Then check the electrical connector of the sensor. Water ingress can cause corrosion of the connector contacts, which then leads to failure or malfunction. If this is the case, the contacts must be cleaned. If the contacts are badly damaged, the only remedy is to replace the temperature sensor.
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