A faulty A/C evaporator temperature sensor that has drifted out of specification or failed completely.; Damaged, chafed, or corroded wiring in the sensor circuit, particularly at the sensor connector or where the harness passes near sharp edges or hot components.; A poor electrical connection at the sensor or PCM connector, often due to water intrusion or loose pins.; An open or short circuit in the sensor signal or ground circuit.; A failed PCM, although this is rare and should only be suspected after all other possibilities are ruled out.; Incorrect sensor installation or a sensor that is not properly seated in the evaporator housing, causing inaccurate temperature readings.

DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P0535

P0535A/C Evaporator Temperature Sensor Circuit

Q: What does code P0535 mean?

A/C Evaporator Temperature Sensor Circuit. P0535 indicates that the powertrain control module (PCM) has detected an abnormal voltage signal from the air conditioning evaporator temperature sensor circuit. The PCM expects the sensor to report a voltage within a calibrated range that corresponds to the evaporator's temperature, and this code sets when the signal falls outside that expected range for a calibrated time period.

P0535 indicates that the powertrain control module (PCM) has detected an abnormal voltage signal from the air conditioning evaporator temperature sensor circuit. The PCM expects the sensor to report a voltage within a calibrated range that corresponds to the evaporator's temperature, and this code sets when the signal falls outside that expected range for a calibrated time period.

SystemPowertrain

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

The air conditioning may blow warm air or fail to cool the cabin effectively.
The A/C compressor clutch may cycle rapidly or not engage at all.
The blower motor may continue running but the air is not chilled.
Often no symptoms besides the warning light, especially if the fault is intermittent.
In some vehicles, the A/C system may default to a fixed setting or disable automatic climate control functions.

Common causes, most likely first

A faulty A/C evaporator temperature sensor that has drifted out of specification or failed completely.
Damaged, chafed, or corroded wiring in the sensor circuit, particularly at the sensor connector or where the harness passes near sharp edges or hot components.
A poor electrical connection at the sensor or PCM connector, often due to water intrusion or loose pins.
An open or short circuit in the sensor signal or ground circuit.
A failed PCM, although this is rare and should only be suspected after all other possibilities are ruled out.
Incorrect sensor installation or a sensor that is not properly seated in the evaporator housing, causing inaccurate temperature readings.

How to diagnose and fix it

Use a scan tool to retrieve the P0535 code and check for any related codes in the climate control system.
Visually inspect the evaporator temperature sensor and its wiring harness for obvious damage, corrosion, or loose connections.
Measure the sensor's resistance with a multimeter and compare it to the manufacturer's specification for the ambient temperature; replace the sensor if it is out of range.
Backprobe the sensor connector to check for reference voltage (typically 5 volts) and a good ground with the key on, engine off.
Perform a wiggle test on the wiring harness while monitoring the sensor signal on a scan tool to identify intermittent faults.
If the sensor and wiring check out, test the circuit from the sensor to the PCM for continuity and shorts to ground or power.
Clear the code and verify the repair by running the A/C system and confirming the sensor signal reads correctly and the code does not return.

Evaporator sensor faults that mimic other issues

A common misdiagnosis is to replace the A/C compressor or recharge the refrigerant when the real problem is a faulty evaporator temperature sensor causing the compressor to be commanded off.
The sensor's resistance changes with temperature, so testing it at room temperature without comparing to the correct specification can lead to a false pass.
On many vehicles, the evaporator temperature sensor is part of the automatic climate control system, and a failure can cause the system to default to a fixed temperature setting or disable automatic mode entirely.
Wiring harness damage near the evaporator housing is often overlooked because the sensor itself is difficult to access, but chafed wires are a frequent cause of this code.
A weak battery or charging system issue can cause erratic sensor readings and set this code, so always verify battery voltage and ground integrity before condemning the sensor.

Can I keep driving with P0535?

The vehicle remains safe to drive because the fault only affects air conditioning performance and does not impair engine operation or safety systems. You can continue driving, but avoid using the A/C until the fault is repaired to prevent potential compressor damage from improper cycling.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.