Code
P0535
Generic
P — Powertrain
A/C Evaporator Temperature Sensor Circuit
Views:
UK: 12
EN: 19
RU: 20
AI status
Completed
Completed
100%
Causes
- Open or shorted sensor wiring or damaged connector
- Corroded or loose connector pins or water intrusion in the evaporator housing
- Faulty evaporator temperature sensor (thermistor)
- Blown fuse or failed HVAC/AC control module (ECU) input circuit
- Intermittent fault from rubbing wire or poor splice
Symptoms
- A/C cycles abnormally or runs continuously
- Reduced A/C performance or blower/defrost issues where the control strategy depends on evaporator temperature
- Diminished ability to prevent evaporator icing (system may stay on/off incorrectly)
- Illumination of MIL or HVAC warning (depending on vehicle)
What to check
- Scan for P0535 and related codes; record freeze frame and live evaporator temperature data
- Visually inspect sensor connector and wiring for corrosion, water, heat damage, pin bending or loose terminals
- Backprobe sensor connector with ignition ON and A/C activated to read signal, reference voltage and ground
- Measure sensor resistance at the connector (with sensor disconnected) and compare to expected thermistor values
- Perform a wiggle test on harness while monitoring live data for intermittent changes
- Check fuses and HVAC/AC control module power/ground and input voltages
Signal parameters
- Reference voltage typically 5 V (varies by manufacturer) — confirm with OEM data
- Sensor signal voltage usually in the ~0.1–4.9 V range depending on temperature (thermistor voltage decreases/increases based on wiring/ECU configuration)
- Typical NTC thermistor behavior: resistance decreases as temperature increases. Example approximate resistances (varies by part): ~30 kΩ at 0°C, ~10 kΩ at 25°C, ~3 kΩ at 50°C — use OEM chart when available
- Expected continuity to ground and stable reference voltage to the sensor circuit; no short to battery voltage or chassis ground
Diagnostic algorithm
- Verify code with a scan tool and note freeze frame/live evaporator temperature readings.
- With ignition ON (A/C active if required), monitor evaporator sensor live value. Confirm value is plausible and changes when the sensor is warmed/cooled (touch sensor or use canned air).
- Visually inspect the sensor harness and connector in the evaporator/heater box for corrosion, water, or physical damage. Repair any obvious issues.
- Backprobe connector: check reference voltage (usually ~5V) and chassis/ECU ground continuity. Look for intermittent loss during a wiggle test.
- With sensor disconnected, measure sensor resistance at known ambient temperature and compare to expected thermistor values from service data. If resistance is out of spec (open/high or short/near 0Ω), replace sensor.
- If sensor resistance is good and reference/ground present but signal stuck/high/low, check for short to power or ground in wiring between sensor and HVAC/PCM; repair wiring as needed.
- If wiring and sensor check OK, scan and test the HVAC control module/PCM input pin for proper operation. Replace control module only after confirming harness and sensor are good.
- After repairs, clear DTCs and perform a functional test of A/C system and monitor sensor live data for correctness and no recurrence.
Likely causes
- Damaged/loose connector at evaporator sensor
- Broken/shorted harness between sensor and HVAC/PCM
- Failed evaporator thermistor
- Corrosion or moisture inside evaporator case or connector
- Failed HVAC control module/input circuitry
Fault status
Status
P0535 — A/C Evaporator Temperature Sensor Circuit: the sensor circuit for the evaporator temperature is reporting an out-of-range or missing signal (open, short, intermittent, or incorrect voltage).
Repair difficulty: Medium
Diagnostic time: 0.5-2 hours
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