AC Contactor Not Pulling In – What Could Be Wrong?

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Problems with AC contactors are normal issues in your AC, but they can cause an unsettling feeling if left unresolved. This can result in your AC unit not functioning correctly when the AC contactor has gone wrong.

Such a thing is annoying and frustrating, especially during the summer. So when the AC contactor not pulling in, what could be wrong? Rest assured! We've got the answer below!

Generally, like any other parts of your AC, in such time, the contactor will go wrong. Corroded contact, faulty coil, and contactor burnout are the common causes of the air conditioner contactor not pulling in.

By the end of this post, you'll learn what causes your AC contactor not to pull in. We'll also touch on how to troubleshoot the contactor. There's a lot to learn from this post. So keep on reading!

Air Conditioning Repair, repairman open case cover air conditioner compressor unit for testing, checking, repairing, AC Contactor Not Pulling In - What Could Be Wrong?

How Does An AC Contactor Work?

The contactor is a component of the air conditioner that regulates how much energy gets into the system. The contactor rises when you switch off your air conditioner, cutting off power.

Once you switch on the AC, the contactor is lifted, allowing energy to power the AC unit. The contactor rises once more when the temperature in your house reaches the setting you set on your thermostat.

Electric relays with normally open and normally closed contacts

The following are the three leading causes of why the contactor becomes bad:

Faulty Coil

Your AC contactors have a coil, and when this coil gets bad, it may ultimately fail. Sometimes, the contactor begins to malfunction, which may manifest as a failure to pull in.

Burnout Contactors

The contactor burns out when the voltage input exceeds its load capacity. Usually, the circuit breaker will trip amid high voltage. If that does not occur, it becomes completely burnt out.

In addition, long cables can also cause your contactor coils to burn because the longer cable can result in voltage loss.

Corroded Contacts

An AC contactor's contact points are vulnerable to corrosion. As tiny particles collect at the point of the contactor, this causes the contact to become dirty, which eventually leads to malfunctioning.

It's crucial to have it checked and replace the contactor regularly to ensure the AC system runs smoothly.

When Should You Replace An AC Contactor?

The following are the common signs and indicators that your AC contactor needs a replacement:

  • AC turns off by itself.
  • AC won't turn on at all.
  • Once it is turned on, the AC takes some time to start.
  • No cool air is coming from the AC.
  • You can hear your air conditioner humming.

How Long Do AC Contactors Last?

A reliable AC contactor typically has a lifespan of 5 to 10 years with the proper care. The technician will assess the contactor's functionality while doing maintenance.

If it is starting to malfunction, the expert will replace the component with less hassle on your part.

How Do You Replace An Air Conditioner Contactor?

The switch that activates the condenser when the contactor drives the inside thermostat signals that extra cool air is necessary.

If the contactor fails, the AC unit will run constantly. By replacing the contactor, you can avoid this problem from inflicting significant damage to your AC system.

To replace your contactor properly, you'll have to:

  1. Turn OFF the AC's circuit breaker.
  2. By testing a voltmeter, ensure no power is left flowing through the AC unit.
  3. Make a mark on all wires for you to easily attach them back later.
  4. Start removing the contactor wires.
  5. Remove the contactor screws using a screwdriver.
  6. Gently remove the contactor.
  7. Securely attach the new contactor.
  8. Reattach the wires accordingly to your marking.
  9. Turn back ON the circuit breaker.

WARNING! This replacement procedure needs proper electrical knowledge. We highly suggest letting the expert do this job for you!

checking & repair of magnetic contactor and fixing air conditioning system

How Much Does An AC Contactor Cost?

The operation of the overall air conditioning system is affected when a contactor fails. Luckily, you can easily find a replacement for a faulty contactor.

Replacement cost varies from $150 to $400 and $10 to $60 for the parts, including the installation.

Nowadays, you can find and hire an HVAC services company to replace the faulty contactor without spending a lot.

Check out this contactor on Amazon.

How Do You Test An AC Contactor?

Typically, two contactors are in your AC, each with a switch identified as a line (L) and a terminal (T). The voltage feed is contained in the line (L), and the terminal (T) is attached to the controlled electrical device.

Engineer´s hand with instrument of measurement and electrical equipment

You can use a voltmeter to test your contactor whether it becomes bad.

Follow this link to see a voltmeter on Amazon.

Use the steps below as a guide to testing an AC contactor correctly.

  1. Carefully remove electrical wires in your contactor line using a screwdriver.
  2. This time again, carefully repeat the process on your terminal side.
  3. Securely attach the contactor control switch to the contactor and switch it ON.
  4. Connect the red lead to the ohm and the black to the common connector.
  5. Switch ON the voltmeter and ensure it's indicating 0 ohms.
  6. Testing all sets of L1 to T1 contacts and connecting the voltmeter red lead to L1 and black lead to the T1.

If the reading fails to show 0 ohms, the contactor is most likely faulty. The regular reading of the contactors is around 5 to 20 ohms.

Furthermore, if one has a failed contactor or coil, you can replace them separately to fix your AC unit if your testing shows no problem with your AC contactor.

NOTE: If the issues persist after all the detailed troubleshooting you've done. It's time for you to hire an AC technician to get this issue finally fixed for good.

Check out this visual from YouTube on testing your contactor:

What Happens When A Contactor Goes Bad?

You can identify a bad AC contactor by signs of breakdown via pitting. Pitting happens when the contactor has excessive exposure to extremely high voltage and heat.

A contactor with pits is likelier to stick, resulting in a constant power supply to the AC unit. If the contactor becomes bad, the AC won't be able to cool the house sufficiently.

Moreover, you can also notice that the AC unit constantly operates while the thermostat is off.

What Are The Types Of Contactors?

Checking contactor by using flat screw

You can find a contactor in two main types, single pole and double pole. A single-pole has a magnetic coil that is attached to a single circuit. In contrast, a double has two coils and is essentially a link in the two circuits.

What's The Difference Between Contactor And Relay?

What Is A Relay?

Relays are switches that run on electricity. A set of functioning contact terminals and a set of input terminals for one or more control signals make up the device.

Any number of contacts, including make contacts, break contacts, and combinations of both, may be present on the switch.

Main Difference

Relays are employed when a circuit has to be controlled by a separate, low-power signal or when multiple circuits need to be controlled by a single signal.

Generally, a contactor is utilized in a primary loop, which can carry a sizable current of 1,000 amps. A relay can only pass through a bit of current and needs a secondary circuit to handle multiple control functions.

Main Function

A contactor's main job is to connect or disengage the main circuit. A relay's primary job is to monitor, transmit, convert, or discard signals. Hence, its on-off current is often low.

The relay often runs the low signal in a controller circuit. Moreover, the circuit whose operation is controlled by the connection with this circuit is referred to as the main circuit.

The term "main circuit" refers to the control circuit with a bigger current than a control circuit.

To Wrap Up

Air Conditioning Repair, repairman open case cover air conditioner compressor unit for testing, checking, repairing

Throughout this post, we learned what causes your AC contactors not to pull in. You also know when you should replace your contactors as needed.

What's more, we've also shared the procedures for how you properly replace the faulty contactor. We can now set off with confidence, knowing that you can now maintain your AC contactor well.

Use this knowledge to your benefit if you encounter common issues with your AC contactor.

Made it this far? Check out these helpful related posts!

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