Heater temperature sensor:
signs of malfunction, diagnostics and replacement of the element 
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Winter trips turn into a challenge when the car heater is not working properly. A cold interior, fogged windows, discomfort for passengers - all this can indicate problems with the heating system.
A small but critically important element is responsible for the correct operation of the heating. This component controls the temperature regime and ensures a comfortable microclimate in the cabin.
Operating principle of temperature sensor
The sensor is a thermistor whose resistance changes with fluctuations in the coolant temperature. The device is mounted directly into the heater radiator or the system’s supply pipe.
Many car owners today encounter malfunctions of this element, especially on cars with a mileage of over 100 thousand kilometers. Wear of contacts, corrosion of the housing, destruction of the sensitive element lead to failures in the operation of climate control.
The main signs of a malfunction include:
- constantly cold air from the deflectors regardless of the settings;
- engine overheating with the heater on;
- chaotic switching of temperature modes;
- lack of response to changes in the position of the temperature regulator;
- errors in the vehicle’s self-diagnosis system.
Diagnosing the problem requires checking the electrical parameters of the sensor with a multimeter. At a temperature of 20°C, the resistance of a serviceable element is 2-3 kOhm.
Replacement and selection of component
The procedure for replacing the sensor depends on the design features of a particular car model. In most cases, access to the element is through the engine compartment or dashboard.
You can buy a heater temperature sensor in specialized auto parts stores or online marketplaces. When choosing, consider the catalog number of the original part and compatibility with the electronic systems of your car.
High-quality sensors from well-known manufacturers serve 80-120 thousand kilometers. Budget analogues often fail after 20-40 thousand kilometers of operation.
The replacement includes several stages:
- disconnecting the battery;
- draining part of the coolant;
- dismantling the old sensor;
- installation of a new element using sealant.
After installation, it is necessary to add antifreeze and remove air locks from the cooling system. Some car models require adaptation of the new sensor via diagnostic equipment.
Prevention and diagnostics of the system
Regular maintenance of the cooling system extends the service life of temperature sensors. Replacing antifreeze every 60 thousand kilometers prevents the formation of deposits on sensitive elements.
Checking the tightness of connections, the condition of pipes, and the performance of the thermostat affects the stability of the temperature regime. Coolant temperature jumps create additional load on the sensors.
Modern cars are equipped with self-diagnostic systems that record error codes when temperature sensors malfunction. Timely reading of diagnostic information helps to identify problems before the component completely fails.
When the first signs of incorrect operation of the heater appear, it is recommended to contact specialists. Ignoring the malfunction can lead to engine overheating and expensive repairs.