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P0539 is a diagnostic trouble code (DTC) for "A/C Evaporator Temperature Sensor Circuit Intermittent". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $69.99. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
When the Powertrain Control Module (PCM) detects a voltage reading from the A/C evaporator temperature sensor that lies outside of the specifications as set by the manufacturer, a P0539 trouble code is stored. Some additional related trouble codes include a P0535, P0536, P0537, and P0538 code.
A variation of either too high or low in the voltage signal coming from the A/C evaporator temperature sensor causes the storage of a P0539 trouble code and the Check Engine light to illuminate.
A faulty evaporator temperature sensor is usually the source of the storage of a P0539 trouble code. Some other reasons for the storage of the code include faulty electrical connections, damaged or shorted wiring, a faulty climate control head, a low refrigerant condition, an overcharged A/C system, or a faulty expansion valve causing the evaporator core to freeze up.
An inoperative A/C system is the most common symptom of a P0539 trouble code. Some other symptoms of this code include the A/C ON indicator flashing repeatedly or the evaporator case freezing up and dripping onto the floorboard of the vehicle.
Diagnosing and repairing a P0539 trouble code requires a mechanic to have certain equipment, including an OBD-II scanner, digital volt/ohmmeter, and a set of air conditioning gauges. The mechanic should also perform the following when attempting to diagnose a P0539 trouble code:
A common mistake made by mechanics when trying to fix a P0539 trouble code is to assume it is caused by a low refrigerant condition. The refrigerant is then overfilled by the mechanic, causing a catastrophic failure. To avoid this, vehicle owners should only have a qualified mechanic, with the proper tools, service the A/C system in their vehicle.
Fortunately, a P0539 trouble code is not that serious, with the most likely symptom a non-working A/C system or, at most, a wet floorboard.
Repairing a P0539 trouble code requires the mechanic to perform certain steps, including:
If, after diagnosing the evaporator temperature sensor or any related circuitry, the mechanic fails to find the source of the problem, the mechanic should suspect a faulty A/C compressor switch or climate control head. The mechanic needs to perform subsequent testing of these components to see if the problem lies there.
YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.