What does it mean?
B2582 is a Body (airbags, seat belts, body electronics) fault code. It indicates: A/C Evaporator Temperature Sensor .
Symptoms
- A/C blows warm, or cold air that turns warm after a few minutes of driving
- Compressor does not engage at all, or cycles on and off far more often than normal
- Evaporator ices up and airflow from the vents drops sharply
- Air temperature swings between cold and warm without any change to the setting
- Automatic climate control cannot hold the selected cabin temperature
- Windscreen demisting is slow because the system cannot dry the air
Likely causes
- Sensor probe pushed out of position or no longer touching the evaporator fins
- Open or shorted sensor element giving a value outside the plausible range
- Corroded or water-damaged sensor connector behind the dash, often below a leaking heater core or blocked drain
- Chafed or broken sensor wiring inside the HVAC housing or under the dashboard
- Blocked cabin filter or matted evaporator fins producing readings the module rejects as implausible
- Low refrigerant charge making evaporator temperature behave abnormally
- Fault in the HVAC control module that reads the sensor
How to fix it
- Read the evaporator temperature value in live data with the engine cold and compare it to ambient temperature; a wildly wrong or fixed reading points at the sensor or its wiring
- Locate the sensor at the evaporator and confirm the probe is seated in the fins rather than hanging loose in the case
- Unplug the sensor and measure its resistance, then compare it against the specification at a known temperature
- Check the connector for corrosion and check for water in the HVAC housing from a blocked evaporator drain
- Test the signal and ground wires back to the module for opens, shorts and high resistance
- Replace the cabin filter and clean the evaporator fins if airflow is restricted
- Verify refrigerant charge and system pressures before replacing the sensor, and evaluate the HVAC module only after the sensor circuit checks out