Repair and Replacement of Temperature Sensors in Air Conditioners: The Main Breakdowns and Their Elimination

Air conditioners are essential appliances in modern homes and businesses, ensuring comfort by regulating indoor temperatures. One of the key components in air conditioners that contribute to their efficient functioning is the temperature sensor. This sensor monitors the room temperature and communicates with the air conditioner’s control system to maintain the desired climate. However, like any other electronic component, temperature sensors can malfunction, leading to various issues with the air conditioning unit. This article delves into the common breakdowns of temperature sensors in air conditioners and how to effectively repair or replace them.


Understanding Temperature Sensors in Air Conditioners


Temperature sensors in air conditioners are typically thermistors, devices that change resistance with temperature variations. These sensors provide critical data to the air conditioner’s microcontroller, which adjusts the compressor and fan speed to maintain the set temperature. The precise functioning of these sensors is crucial for the air conditioner’s efficiency and the comfort of the occupants.


Common Breakdowns of Temperature Sensors


Sensor Drift:

Over time, temperature sensors can experience drift, where the sensor’s readings become less accurate. This can happen due to prolonged exposure to extreme temperatures or gradual degradation of the sensor’s materials. Sensor drift can lead to incorrect temperature readings, causing the air conditioner to overcool or undercool the space.


Open Circuit:

An open circuit in a temperature sensor occurs when the sensor’s wiring is damaged or disconnected. This can be due to physical damage, corrosion, or poor connections. When an open circuit occurs, the air conditioner may display error codes or fail to operate altogether, as it cannot receive accurate temperature readings.


Short Circuit:

A short circuit in the temperature sensor usually results from moisture ingress or damage to the sensor’s insulation. This causes the sensor to send continuous, incorrect signals to the air conditioner’s control system, often resulting in the system running non-stop or failing to start.


Thermistor Failure:

Thermistors can fail due to various reasons such as electrical surges, manufacturing defects, or wear and tear over time. A failed thermistor will generally result in erratic behavior of the air conditioning system, such as inconsistent cooling or frequent cycling on and off.


Diagnosing Temperature Sensor Issues


Before attempting any repairs or replacements, it is essential to diagnose the problem accurately. Here are some steps to diagnose temperature sensor issues:


Visual Inspection: Check the sensor and its connections for any visible signs of damage, corrosion, or disconnection.


Error Codes: Modern air conditioners display error codes on the control panel or remote. Refer to the user manual to interpret these codes, which often indicate specific sensor problems.


Multimeter Testing: Use a multimeter to check the resistance of the thermistor. Compare the readings with the specifications provided in the air conditioner’s service manual. Deviations from the expected values indicate sensor issues.


Repairing Temperature Sensors


Fixing Connections:

If the problem lies in the wiring or connections, re-soldering the connections or replacing damaged wires may resolve the issue. Ensure the connections are secure and free from corrosion. Use heat shrink tubing to insulate the connections properly.



Sometimes, the sensor or its connections may just need cleaning, especially if located in a humid or dusty environment. Use a soft brush and isopropyl alcohol to clean the sensor and connectors.



In cases of sensor drift, recalibrating the sensor may help restore accuracy. This can often be done by adjusting the control board settings if the air conditioner model allows it. Refer to the service manual for specific recalibration procedures.


Replacing Temperature Sensors


When repair is not possible or practical, replacing the temperature sensor is the next step. Here’s how to do it:


Power Down: Ensure the air conditioner is unplugged from the power source to avoid electrical shock.


Locate the Sensor: Refer to the air conditioner’s service manual to find the temperature sensor. It is usually located near the evaporator coil or on the control board.


Remove the Old Sensor: Disconnect the sensor from its wiring or connectors. Carefully remove any clips or fasteners holding the sensor in place.


Install the New Sensor: Connect the new sensor to the wiring, ensuring it matches the original connections. Secure the sensor in its designated position.


Test the System: After replacing the sensor, restore power to the air conditioner and test it. Check for correct operation and any error codes.


Preventive Maintenance


To prolong the life of temperature sensors and avoid frequent repairs or replacements, regular maintenance of the air conditioner is crucial:


Regular Cleaning: Keep the air conditioner and its components clean, including filters, coils, and sensors.

Proper Usage: Avoid setting the temperature too low, which can cause excessive wear on the components.

Scheduled Servicing: Have a professional technician inspect and service the air conditioner periodically.


Temperature sensors are vital to the efficient operation of air conditioners. Understanding the common breakdowns and how to diagnose, repair, or replace these sensors can help maintain optimal performance and extend the life of the air conditioning unit. Regular maintenance and timely intervention are key to avoiding major disruptions and ensuring a comfortable indoor environment.


Don’t delay your air conditioner repair. Do not forget that repairing is much easier and cheaper immediately after a breakdown occurs. If your air conditioner is working, but making strange noises or not cooling the room enough, it means it’s time to contact the technicians.


Don’t wait until the air conditioner is completely out of order. In the case of untimely repairs, there is a very high possibility that a long complex repair will be required. Even a few days without air conditioning in the summer heat in San Diego County, CA will bring great discomfort to the whole family. But by calling the masters from SDAC Heating & Air Conditioning you can avoid this problem.


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