Possible Reasons For AC Contactor Failure In Your Home

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Your AC utilizes a system of components to cool your home effectively. These include a contactor that provides and controls power to parts such as the compressor and condenser fan. Unfortunately, the contactor may deteriorate over time, causing it to fail electrically and mechanically. This may result in the evaporator and condenser coils cracking, as well as a spike in your energy bills. Thus, it is wise that you hire an HVAC professional for a diagnostic callout. They will inspect your unit and identify and repair the defect for peak performance. Below are some reasons for AC contactor failure:

Temperature Rise

If you fail to replace the appliance's filters, they may clog over time, restricting airflow. This causes the system to strain in drawing sufficient air for cooling, causing it to overheat. Dirt and debris accumulation on the condenser can also inhibit heat release, resulting in heat build-up. This leads to the compressor working too hard, leading to burnout. As a result, heat retention in the system raises the contactor's temperature, reducing its efficiency. Therefore, you should engage an AC technician to clean the unit and facilitate proper airflow.


As your cooling system ages, it sustains a lot of wear and tear. Accordingly, the contactors are subject to wear both from aging and the effects of arcing. The wear causes the resistance across the connection to increase, raising heat generation. Moreover, condensation may seep into the contactor, corroding the poles of the contactor's magnet. Consequently, rust on the contacts creates additional heat that causes it to burn out. For these reasons, contacting an AC contractor to replace the contactors and install transistors to manage thermal performance effectively is prudent.

Voltage Fluctuation

Obstructions in the transmission may cause voltage fluctuation, affecting the contactor's performance. This is because every contactor has an operational limit of the rated coil. Hence, the electromagnetic closing will increase and burn the coil due to over-voltage. Conversely, an under-voltage will decrease the electromagnetic closing, resulting in a delay in the contactor's operation. As such, you should employ the services of an HVAC repair expert to install voltage stabilizers to limit power fluctuation.

Coil Overcurrent

This condition occurs when the motor draws excessive amounts of currents. It may result from an aging compressor that experiences a hard start when you turn on the system. Consequently, the motor draws more electricity, causing the electromagnetic coil to burn and tripping the circuit breaker. For the contactor's seamless operation, you need to hire an AC technician to fix the electrical malfunction.

The contactor could be malfunctioning if you hear humming, chattering, or buzzing. So, contact an HVAC repair specialist to fix the contactor for you.