What does it mean?
P1436 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: A/C Evaporator Temperature (ACET) Circuit Low Input .
Symptoms
- MIL or an air conditioning warning displayed, depending on the vehicle
- Compressor operation limited or switched off entirely, because the module rejects an out of range sensor value and falls back to a safe strategy
- Where the low signal is instead accepted as a very high evaporator temperature, the compressor runs almost without pause and the evaporator can ice up, choking airflow
- Evaporator temperature parked at one extreme of the scale in live data and no longer following vent temperature
- Blower operation unaffected, so the fault is easy to mistake for low refrigerant
Likely causes
- Signal wire shorted to ground in the harness behind the dashboard
- Sensor element internally shorted, giving almost no resistance
- Water dripping from a blocked evaporator drain into the sensor connector
- Corroded or wet connector terminals bridging signal and ground
- Pinched wiring where the harness passes the heater box or dash brackets
- Damaged harness after previous dashboard or blower motor work
- Loss of the sensor pull up reference inside the control module, which some systems report as a low input
How to fix it
- Read the evaporator temperature in live data with the system off and compare it with the ambient temperature
- Disconnect the sensor and check whether the reported value swings to the opposite extreme; if it does, the sensor is at fault
- Measure the sensor resistance and compare against its temperature to resistance chart
- Inspect the connector for moisture and corrosion, and check the evaporator drain for blockage that lets water pool
- Test the signal wire for a short to ground with the sensor and the module both disconnected
- Check the harness behind the dash for pinched or damaged sections from previous work
- Replace the sensor or repair the shorted wire, then verify that the evaporator reading tracks vent temperature and that the compressor cycles normally