P0535

P0535 sets when the ECU detects a generic circuit fault on the A/C evaporator temperature sensor - the sensor that monitors evaporator coil temperature to prevent icing during long A/C operation. The ECU/HVAC module uses this signal to cycle the A/C compressor off before the evaporator drops below freezing and ices up. Cheapest-first ladder: (1) Locate the sensor - typically inserted into the evaporator core inside the HVAC housing behind the dash, with a connector accessible from inside the passenger footwell area. (2) DMM the sensor resistance and compare to ambient temp - typical NTC thermistor behavior, 10k ohms near 25C dropping as temp rises. (3) Inspect the connector for moisture - HVAC evap sensors live in a high-condensation environment and corroded pins are common. (4) Scope the signal with the engine and A/C running, watching for the sensor to track evaporator temperature as the system cycles. Expensive-misdiagnosis trap: replacing the HVAC control module when a $30 evaporator temp sensor was the actual fault.

Vehicle-specific patterns: 2003-2010 Chrysler 300 / Dodge Charger / Magnum throws P0535 from corroded evap-temp sensor connectors. 2007-2014 GM full-size trucks (Silverado, Tahoe, Yukon) throw P0535 from a failed evap thermistor with poor service-time accessibility. 2008-2013 Honda Accord / Pilot throws P0535 from connector moisture intrusion. 2010-2016 Ford F-150 / Edge / Explorer throws P0535 from a known evaporator sensor failure pattern on the Ford-supplied component. Estimated repair: $80 to $350