how to buy ac contactor



Are you in the market for an AC contactor but unsure of how to proceed with the purchase? Look no further, as this article will guide you through the process of buying an AC contactor. AC contactors are essential components of air conditioning systems, responsible for controlling the flow of electricity to the compressor and regulating the system's overall functionality. Whether you are a homeowner or an HVAC professional, understanding the key factors to consider when purchasing an AC contactor is crucial. In the following sections, we will discuss the various aspects you should evaluate to make an informed decision.

Selecting the Right Type of Contactor

AC contactors come in different types, each suitable for specific applications. It is crucial to identify the appropriate type for your requirements before making a purchase. Here, we will discuss three common types of AC contactors:

Main Contactors

Main contactors are designed to handle the high electrical load required to power an air conditioning system. They possess robust construction and are typically used for residential and commercial applications. When selecting a main contactor, consider the voltage and current ratings that match your air conditioning system's specifications. Additionally, assess the coil voltage compatibility and ensure it matches your existing control system.

Auxiliary Contactors

Auxiliary contactors, also known as auxiliary switches, are used to control and monitor additional electrical devices or functions. These contactors are often employed in complex air conditioning systems that require multiple control signals and connections. When choosing auxiliary contactors, ensure compatibility with your existing system's control interface.

Lighting Contactors

Lighting contactors are specifically designed for controlling lighting circuits in large commercial or industrial spaces. If you aim to integrate your air conditioning system with lighting control, opt for a contactor with lighting-specific features. These contactors often include various control methods, such as timers or photocells, to automate lighting operations.

Consider the specific needs of your air conditioning system and select the appropriate type of contactor that aligns with your requirements.

Understanding Contact Ratings

Contact ratings are essential specifications to consider when buying an AC contactor. They indicate the maximum current and voltage the contactor can safely handle. It is crucial to choose a contactor with ratings that match or exceed your air conditioning system's electrical demands. Here are some key contact rating parameters to consider:

Current Rating

The current rating specifies the maximum electrical current the contactor can carry. It is crucial to select a contactor capable of handling the current required by your air conditioning system's compressor and other components. Choosing a contactor with insufficient current rating may result in premature failure or even damage to the electrical system.

Voltage Rating

The voltage rating indicates the maximum voltage the contactor can safely handle. It is crucial to ensure the contactor's voltage rating matches the voltage supplied to your air conditioning system. Compatibility in voltage rating is vital to prevent electrical arcing, which can lead to equipment damage or electrical hazards.

Inductive Rating

Inductive rating refers to the contactor's ability to handle inrush current, which occurs when an electrical component first receives power. Since air conditioning compressors often exhibit high inrush currents during startup, selecting a contactor with an appropriate inductive rating is necessary to ensure reliable operation.

Coil Voltage

The coil voltage is crucial as it determines the voltage required to energize the contactor and close the electrical circuit. It is essential to choose a contactor with a coil voltage compatible with your control system. Verify the voltage supply of your control circuit and select a contactor accordingly to ensure proper operation.

Identifying Form Factors and Mounting Options

Form factors and mounting options play a significant role in determining the compatibility of an AC contactor with your system's physical configuration and available space for installation. Here are a few key considerations:

Enclosure Type

AC contactors come in various enclosure types, such as open or enclosed. Open types are suitable for protected indoor environments, whereas enclosed types offer additional protection against dust, moisture, or physical damage. Assess the environmental conditions of your installation site and choose an appropriate enclosure type accordingly.

Pole Configuration

Pole configuration refers to the number of electrical poles within the contactor. Common configurations include single pole (SPST), double pole (DPST), and three-pole (TPST or TPDT). Select a contactor with a pole configuration that matches your air conditioning system's electrical requirements.

Mounting Options

Depending on your installation requirements, you may choose between DIN rail mounting, panel mounting, or base mounting options. Ensure the chosen contactor's mounting style aligns with your installation needs and available space.

Evaluating Reliability and Longevity

Reliability and longevity are crucial factors when selecting an AC contactor. Investing in a reliable and durable contactor ensures the smooth operation of your air conditioning system and reduces the frequency of maintenance or replacements. Here are a few aspects to consider regarding contactor reliability:

Brand Reputation

Choose contactors from reputable brands known for producing high-quality electrical components. The reputation of a brand often indicates their commitment to manufacturing reliable products. Extensive research and consumer feedback can help identify brands with a history of producing dependable contactors.

Product Certification

Verify whether the contactor carries necessary certifications, such as UL (Underwriters Laboratories) or CE (Conformité Européene), indicating compliance with safety and performance standards. Certified products undergo rigorous testing to ensure reliability and safety.

Customer Reviews

Consider reading customer reviews and testimonials regarding specific contactor models. These insights can provide valuable information about the product's performance in real-world applications. Look for consistent positive feedback and consider any common issues or concerns mentioned by users.

Warranty Coverage

Review the warranty provided by the manufacturer. A longer warranty period often signifies the manufacturer's confidence in the product's reliability and durability. Ensure that the warranty terms are reasonable and cover potential failure scenarios.

Ultimately, investing in a reliable contactor will contribute to the longevity and efficiency of your air conditioning system, reducing the risk of unexpected breakdowns or malfunctions.

Sourcing and Pricing

Once you have determined the specific requirements and features you need, it's time to identify reliable sources and compare prices. Here are some avenues to explore:

Manufacturer's Websites

Visit the official websites of reputable contactor manufacturers. These websites often provide detailed product information, specifications, and compatibility charts. Some manufacturers may also offer direct online purchasing options.

Distributors and Retailers

Contact local HVAC distributors or retailers and inquire about the availability of specific contactor models. These professionals can provide guidance, recommendations, and access to a wide range of contactor options.

Online Marketplaces and Suppliers

Explore online marketplaces and suppliers specializing in HVAC components. Platforms like Amazon, eBay, and specialized HVAC online stores offer a broad selection of contactors. Ensure that you are purchasing from trustworthy sellers with positive ratings and reviews.

When comparing prices, consider the overall value provided by the contactor, including features, reliability, and warranty coverage. Opting for the cheapest option may not always yield the best long-term results. Strike a balance between cost and quality to ensure a worthy investment.


Purchasing the right AC contactor is essential for the smooth operation of your air conditioning system. By considering factors such as contact ratings, form factors, reliability, and pricing, you can make an informed decision. Remember to assess your system's specific requirements and consult professionals if needed. With the right AC contactor in place, your air conditioning system will remain reliable, efficient, and functional for years to come.


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