Why Is My AC Sensor Not Working?

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Updated August 19, 2022

Even if you have a top-tier air conditioner unit, you cannot have dependable cooling with a faulty thermostat. AC temperature sensors detect your home’s air temperature. Once the indoor climate rises above the cool setting on the control panel, the air conditioning unit activates the AC cycle. A lousy sensor causes inconsistent signals to the AC’s on-off cycle, leading to erratic cycling and minimal temperature control. Read this guide to learn, “Why is my AC sensor not working?”


  • An AC sensor detects your air temperature and signals your air conditioner to cool your home.
  • A faulty sensor causes an AC to run inconsistently or turn off before it finishes the cooling cycle.
  • If your temperature sensor is dislodged or incorrectly installed, it cannot accurately detect your evaporator coil, leading to lackluster cooling.

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Why Is My AC Thermostat Sensor Broken?

A faulty temperature sensor can trigger inconsistent cooling or continuous operation, leaving you wondering, “Why does my air conditioner run all the time?” Additionally, a broken sensor causes extra energy usage, even in an energy-efficient window air conditioner.

It takes an entire air conditioning system and functioning internal components, like air conditioning sensors, to cool your home. By knowing what temperature to set the air conditioner when you’re away and performing regular maintenance, you can investigate and prevent faulty sensors in your AC.

Insider Tip

You must install the thermostat in a central location in your home and away from direct sunlight.

Broken Thermostat

A faulty thermostat cannot accurately track your current temperature, which causes the AC unit to run at odd times or continuously past your desired temperature.

Displaced Sensor

The AC sensor measures your air temperature as it enters the evaporator coils. If your AC sensor is dislodged through damage or improper installation, it cannot accurately track on-off cycles, and the system will run irregularly. Check to see if a wire might have been damaged or loosened.

Signs of AC Sensor Issues

Some common air conditioning problems happen naturally over time, but others occur because of inadequate maintenance. Luckily, it doesn’t take a repair technician to diagnose the issue. You can spot a defective temperature sensor by paying attention to the warning signs below.

Erratic Cycles

An AC with a bad sensor will run randomly and deliver uneven cooling throughout your home. If your AC kicks on too early or shuts off before the cooling cycle finishes, you need a prompt AC repair on your temperature sensor.


Disconnect the electrical connection to your AC before inspecting the internal coils and parts; otherwise, you risk serious injury or death from electrical shock.

High Energy Bills

Without an accurate sensor reading, your AC unit may continue to run when it isn’t needed. These extended cycles will cause excess energy usage and higher-than-normal energy bills. Increased power consumption points to multiple AC failure points, so experts recommend contacting an AC repair expert.

STAT: A 2020 US EIA (Energy Information Agency) survey found that 15% of Americans set their air conditioner system at 70 degrees. (source)

Why Is My AC Sensor Not Working FAQs

How do I fix an AC sensor?

If your AC sensor is dislodged, you can bend it back into place. Disconnect the circuit breaker connected to the AC and remove the access panel. Find the evaporator coil, and reposition the sensor.

How do I reset my AC sensor?

You can reset your AC system through a power cycle. Turn off the circuit breaker connected to the AC, and wait one minute before reactivating the power. Next, wait 30 minutes and allow the AC's internals to reset. Lastly, power the AC back on, and reset your desired temperature.

How do you clean an AC sensor?

You can clean the AC sensor with water or white vinegar like other AC internals. That said, you need to be cautious not to bend the sensor out of position while cleaning it.
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