What are the symptoms of a faulty car air conditioning temperature sensor?
3 Answers
The specific symptoms of a faulty car temperature sensor are as follows: 1. Intake air temperature sensor: If the intake air temperature sensor malfunctions or is damaged, the engine will not be able to accurately calculate the fuel injection amount, resulting in a mixture that is either too rich or too lean. The car may experience difficulties starting, unstable idling, shaking, or black smoke emissions, affecting engine performance. 2. Coolant temperature sensor: If the coolant temperature sensor malfunctions or is damaged, the engine will not be able to regulate the water temperature in time, leading to insufficient cooling. This can easily cause overheating or cylinder scuffing. Symptoms include difficulties starting when cold, unstable idling, shaking, and weak acceleration. 3. Inspection of the outside temperature sensor: The outside temperature sensor, also known as the ambient temperature sensor, is usually installed near the front bumper or grille. Its sensing element uses a negative temperature coefficient thermistor. The inspection method for the outside temperature sensor is the same as that for the coolant temperature sensor. You can use a multimeter's resistance setting to measure its resistance value. At room temperature, the resistance should be 1.6-1.8KΩ, and the resistance increases as the temperature decreases.
When I drive, the air conditioning always acts up. For example, the set temperature doesn't match the actual airflow—it blows cold air at 30°C or hot air at 28°C, which is baffling. The compressor also behaves erratically, making constant clicking noises as if it never stops. I thought it was an AC setting issue, but repeated adjustments didn’t help. Later, it turned out the temperature sensor was faulty. It misreads the ambient temperature, causing the system to misinterpret commands. This problem is common in summer, making the car feel like a sauna and ruining driving comfort. In winter, it’s worse—windows may frost over, obstructing visibility, which is dangerous. If left unfixed, it also increases fuel consumption due to the compressor overworking. I recommend getting a mechanic to check the sensor early to avoid bigger issues. Similar symptoms like unstable airflow or strange odors are also worth noting.
When I notice abnormal air conditioning, I typically observe several characteristics to determine if it's a temperature sensor failure: First, check whether the displayed temperature on the control panel contradicts the actual feeling—for example, showing 20°C but feeling excessively hot or cold. Frequent compressor cycling (starting and stopping) is another sign, often causing loud noises. If the automatic climate control malfunctions and manual adjustments prove ineffective, it usually points to a sensor issue. Scanning for error codes with a diagnostic tool is straightforward, as most vehicle models will report faults like P0112 or P0113. In daily use, sensors are prone to dust accumulation, so I try cleaning them first. Early diagnosis saves trouble; otherwise, it may lead to evaporator icing or damage, and prolonged neglect could result in costly repairs. As a side note, poor wiring connections or aging components can also cause similar symptoms, so a thorough inspection of the AC system is crucial.
