How do I know if my car evaporator is bad?
Mar 03, 2025
Common Fault Symptoms:
Abnormal Cooling Performance:
Reduced airflow and lower-than-usual temperatures (even freezing), resulting in poor cooling efficiency.
Complete failure of cooling or extremely slow temperature drop.
Unusual Odors and Leaks:
Detection of refrigerant or refrigerant oil-like smells inside the vehicle.
Liquid leakage (e.g., fluorescent dye or refrigerant) from the evaporator drain pipe.
Mechanical and Operational Issues:
Compressor operating continuously under high load with noticeable noise or abnormal sounds.
Visible oil stains, carbon buildup, deformation, or corrosion on the evaporator surface.
Testing Methods:
Initial Inspection:
Visual Examination: Check for cracks, corrosion, or leaks in the evaporator.
Temperature Assessment: Measure the temperature at the AC vents. A significant deviation from the normal range (e.g., below 10℃ and weak airflow) may indicate evaporator icing or blockage.
Professional Diagnostic Tools：
Fluorescent Dye Test: Inject fluorescent dye into the refrigerant system and observe leaks via the drain pipe under UV light.
Fluorine Detector: Use a leak detector at vents; an alarm signals refrigerant leakage.
Pressure Test: Measure system pressure with a manifold gauge; abnormal low-side pressure may indicate blockages or damage.
Leakage Testing: After removing the evaporator, apply pressure and submerge it in water to check for air leakage.
Additional Factors for Consideration:
Compressor Behavior: Frequent cycling or continuous operation without effective cooling may signal faulty evaporator temperature sensors.
Vehicle Performance: Severe evaporator issues may correlate with reduced engine power or increased fuel consumption due to excessive compressor load.
Note: If symptoms arise, start with visual and temperature checks, then confirm faults using fluorescent dye or pressure tests. Timely repair is critical to prevent compressor damage or complete AC system failure.
