BMW X3 Air Conditioner faulty

The car evaporator (or evaporator coil) is an essential component of the air conditioning system, responsible for absorbing heat from the car's interior and facilitating the evaporation of refrigerant to achieve cooling. When the evaporator is damaged or malfunctioning, it can manifest the following symptoms:   1.Decreased cooling effect: Even with the AC turned on and the fan operating properly, the air blowing out of the vents is not cool or fails to provide any cooling at all. This can be attributed to evaporator leaks, blockages, or internal damage, resulting in reduced heat exchange efficiency.   2.Reduced airflow: The air volume from the air vents noticeably diminishes, even when set to maximum. This could be caused by ice formation on the evaporator's surface (due to refrigerant leaks or temperature control issues), obstructing the airflow.   3.Unpleasant odor in the car: A strong musty or sour smell is detectable when the AC is switched on. This can result from prolonged moisture accumulation and mold growth in the evaporator (often caused by clogged drain holes) or the mixing of leaked refrigerant with other odors.For example, the evaporator of this BMW X3 below.       4.Unusual noises from the AC system: Hissing sounds (indicating refrigerant leaks) or gurgling sounds (suggesting internal blockages) can be heard while the AC is running. It's important to distinguish these noises from those originating from the compressor.   5.Damp or water accumulation on the car's floor: The carpet below the passenger side (where the evaporator is located) feels damp or even collects water. This occurs when the drain pipe of the evaporator is clogged, preventing condensation from properly draining and resulting in backflow into the car interior.   6.Abnormal AC system pressures (requires professional diagnostics): During testing by a repair shop using pressure gauges, abnormal pressures are observed on the high and low sides (e.g., excessively low pressure on the low side). This indicates evaporator leaks or blockages causing improper refrigerant circulation.   Based on the aforementioned symptoms, further confirmation can be obtained through the following methods: Visual inspection: Removing the AC filter or certain control panel components and using an endoscope to examine the evaporator for signs of ice formation, oil stains (indicating refrigerant leaks accompanied by oil leakage), or corrosion. Fluorescent detection: Injecting fluorescent dye into the AC system and inspecting the evaporator under UV light for any leak points. Professional diagnosis: Visiting a repair shop to perform tests using AC pressure gauges, electronic leak detectors, or conducting performance tests on the AC system.   In conclusion, common causes for a malfunctioning evaporator include refrigerant leaks (resulting from corroded or punctured evaporator coils or aging seals), blockages (caused by expansion valve or pipe impurities leading to ice formation), and mold growth (caused by long-term lack of AC system cleaning or poor drainage).   If there is suspicion of evaporator failure, it is recommended to have it repaired promptly to prevent potential damage to the compressor (due to insufficient refrigerant lubrication). The replacement of the evaporator requires dismantling the control panel and incurs higher labor costs, so it is advisable to choose a reputable repair facility. Additionally, it should be noted that certain symptoms (such as lack of cooling) can also be caused by other factors (such as insufficient refrigerant or compressor failure), requiring a comprehensive diagnostic approach.