A/C Evaporator Temperature Sensor Circuit Malfunction
The P0535 code indicates a problem in the circuit of the A/C evaporator temperature sensor, which monitors the temperature of the evaporator core to prevent freezing and regulate A/C operation. The PCM detects a voltage signal outside the expected range, often due to a faulty sensor, wiring issues, or a short circuit. This can cause the A/C system to malfunction, such as intermittent cooling or the compressor not engaging.
1. Most Common Causes
- Faulty evaporator temperature sensor
- Open, shorted, or high-resistance wiring in the sensor circuit
- Corroded, oxidized, or loose pins at the sensor connector
- Failed HVAC control module or PCM
- Incorrect refrigerant charge (too low or too high) affecting evaporator temperature
- Restricted airflow across the evaporator core
2. Symptoms You Will Notice
- A/C system blows warm air intermittently
- A/C compressor fails to engage
- Erratic or no cooling from A/C
- Check Engine Light illuminated
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm code P0535 and check for related codes.
Step 2: Visually inspect the A/C evaporator temperature sensor and its wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor's resistance with a multimeter; compare to manufacturer specifications (typically 2-10 kΩ at room temperature).
Step 4: Check for voltage and ground at the sensor connector with the ignition on; repair any open or short circuits found.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, it is generally safe to drive, but the A/C may not work properly. Prolonged driving without A/C could cause discomfort, but no immediate mechanical damage.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150, including parts (sensor $20-$50) and labor (0.5-1 hour).
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.