How to Fix a Stuck Relay on AC Unit: A Few Easy Steps

A stuck relay is a common AC issue. Fortunately, you can easily fix the problem on your own provided you have some information about AC units.
By
Carolina Evans
Carolina Evans
Research Writer
Holds a Master’s degree in Engineering and is keen on her own home’s climate. Sometimes we think that Carolina owns every single product she writes about – that’s ho read more
reviewed
Reviewed By
Richard Powell
Richard Powell
Expert Consultant
For 8 years, Richard had been working as an HVAC specialist and AC unit installer since his student years. Now, he’s our main consultant on every technical aspect that may read more
Last updated: December 28, 2022
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Has your air conditioner been acting weird lately? When your air conditioner stops functioning efficiently, there must be an issue with one of its components. If you test the thermostat or the circuit, and they seem okay, the problem could be a stuck relay.

If the AC relay gets stuck, your unit won’t turn on or off and may eventually break down. Before you think of replacing it, you may want to fix it first. This article offers helpful information on how to fix a stuck relay on your AC unit. Let’s dive right in!

What Is a Relay?

How to Fix a Stuck Relay on AC Unit: A Few Easy Steps

An AC relay is a switch usually located on the outdoor unit. This component is connected to three wires, including the ground wire, the control board’s input wire, and the power feed wire to the AC compressor clutch.

The main function of this component is to regulate electric current flow to your air conditioner, enabling you to turn the AC motor on or off. When you turn on your AC unit, the relay closes, allowing electricity to flow into the unit. On the other hand, when you switch off your air conditioner, the relay opens, breaking the circuit. As a result, electricity will not flow into your unit.

Generally, the relay plays a crucial role in the energy efficiency of your air conditioner, depending on the type or how well you maintain it.

Why Does an AC Relay Get Stuck?

All AC relays may develop issues at some point. There are several factors that can make your AC relay get stuck. Some of the common reasons include:

  • Dirty contact relay
  • Low refrigerant levels
  • Short circuit
  • Faulty pressure switch
  • Faulty control switch

Signs of a Stuck Relay

When your AC’s relay gets stuck, your unit will show some signs. In this section, we shall highlight the signs to watch out for.

  • Your AC provides inconsistent cooling – The thermostat usually receives commands through the relay. Therefore, if the relay is not functioning properly, the thermostat can’t complete the request, and you may experience inconsistent cooling.
  • Your AC unit refuses to turn off – If the relay on your  AC unit Trusted Source Common Air Conditioner Problems | Department of Energy When your air conditioner is not operating properly, there are a few things you can check before calling a service professional. www.energy.gov becomes stuck, it will remain in the open state. As a result, your AC’s components won’t turn off, wasting your energy.
  • The AC unit refuses to turn on – When the relay gets stuck, the compressor won’t get enough power, meaning your unit won’t turn on completely.
  • Rattling noise – If you hear rattling noise coming from your unit even after turning it off, the relay is stuck.
  • Visible damage – When you use your AC unit for some time, its components, including the relay, may become old or get damaged. A damaged relay may get stuck and prevent your unit from running efficiently.

If you notice any of the signs above, test the relay with a multimeter to be sure. For accurate results, consider using one like the Crenova MS8233D Auto-Ranging Digital Multimeter.

How to Fix a Stuck Relay on Your AC Unit

A stuck relay does not mean the component is completely useless since you can fix it and ensure it operates efficiently. Here are some methods you can use to fix a stuck relay:

Clean the Relay

When dust particles accumulate on your relay, it may get stuck. Therefore, if you want your relay to operate efficiently, you need to clean it.

Before cleaning the relay, you have to locate it first. AC relays are located on different parts depending on the model. You can find your AC’s relay location by going through the user manual or just searching on the internet.

The best way to clean the relay is to remove it from the unit and gently wipe it with a rag dipped in vinegar or alcohol. Remember to cover the wires with masking tape before cleaning the component to protect them from damage. After that, allow it to dry off completely before replacing it.

If you don’t have the time to clean your AC regularly, consider buying a unit with a dust feature, such as the Frigidaire FFRA051WAE Window-Mounted Room Air Conditioner. This component will prevent dust from entering the unit and settling on the relay.

Knock the Relay Several Times

A relay is an electromechanical switch meaning it has several moving components. Therefore, when your relay gets stuck, try knocking it several times, especially if there is no major issue, and see if it will start functioning properly. Although this method is effective, it may not work at all times.

Replace the Relay

If you’ve tried cleaning the relay or knocking it several times, but it still refuses to function efficiently, it’s time to replace it. Additionally, if the relay has visible damage, the best solution would be to replace it.

When buying a relay for your AC unit, it’s important to get one that’s compatible with your unit. Otherwise, it won’t function properly. After that, take out the old relay and install the new one.

Replacing the relay is not a complicated process, provided you have some knowledge of air conditioners. You can also consult the user manual or Google to avoid making mistakes. If you’re not sure, seek the help of a professional HVAC contractor.

How to Replace a Relay of an AC Unit?

If you decide to replace the AC relay by yourself, there are various steps that you should follow, as discussed below.

Get the Right Relay

When buying a new relay for your AC, check if it matches the old one. Ensure both relays have the same design, shape, and electrical specifications.

Disconnect power

How to Fix a Stuck Relay on AC Unit: A Few Easy Steps

Before replacing the relay, switch off the air conditioner’s circuit breaker. Alternatively, you may disconnect the switch. This step is important since relays serve as the intermediaries for transferring electric current throughout the air conditioner. Therefore, you may get electrocuted if you don’t turn off the power.

Keep Track of the Terminal ID

Your relay has some wires which enable it to operate efficiently. Tape the wires using masking tape and write on them the relay’s terminal identification numbers, which are located next to each terminal.

However, some relays, such as the condensing-unit contactors, lack terminal identification numbers. In such a scenario, you should write different numbers on the masking tape of each wire and then draw the relay on a piece of paper and label each wire’s terminals with its corresponding number.

Pull the Terminal Connector

How to Fix a Stuck Relay on AC Unit: A Few Easy Steps

Get needle-nose  pliers Trusted Source Pliers Information Pliers (plyers) are handheld, manually-powered hand tools, often employing serrated jaws, designed for holding, cutting, bending, or manipulation of tough or difficult materials such as wire, sheet metal, or fine machine components. www.globalspec.com , and separate the wires from the terminal connector. You can also use it to hold the connectors and not the wires. Avoid gripping the wires since the pliers can completely destroy them.

Unscrew the Relay

The relay is usually screwed to the air conditioning unit. To replace the relay, you have to unscrew it first using the correct screwdriver.

Install the New Relay

How to Fix a Stuck Relay on AC Unit: A Few Easy Steps

Remove the old relay from the air conditioner and place the new one.  Use the screws that held the old relay to secure the new one in the air conditioning unit.

Final Touch

After securing the new relay, push the wires into the respective terminals using the drawing or tape tags as a reference. Afterward, push the connector over the relay’s terminal using the pliers. The wire connectors need to fit snugly over the relay’s terminals.

How to Prevent the Relay from Becoming Stuck

You can easily protect your relay from getting stuck using the following methods.

Use Your Air Conditioner Sparingly

Air conditioners usually produce heat when they are in use. Therefore, using the equipment regularly will produce a lot of heat, making the relay material melt. When the melted material cools, it will stick together, and the relay may get stuck.

The best way to prevent this issue is by using your air conditioner sparingly. For instance, remember to turn off your AC unit whenever it’s not in use. However, this can be challenging, especially if you are not around. Therefore, you should consider investing in an air conditioner with a smart control feature to help you turn it off from wherever you are. According to most reviews, Friedrich CCW15B10A Chill Premier Smart Air Conditioner Wall & Window Unit is the best AC to buy if you want a unit with effective smart functionalities.

Keep Your AC Outdoor Unit Clean

Preventing dust and debris from getting inside your AC’s outdoor unit is almost impossible. The only thing you can do is clean it regularly to prevent the dirt from accumulating. Besides cleaning the unit, you should also consider cleaning the coils and replacing the  air filters Trusted Source Characteristics of Air Filters Air filter is the main equipment in the field of air cleaning technology, and it is an indispensible equipment to create the clean air environment. So it is necessary to know the characteristic of air filters and its design principle so as to use it correctly and effectively. www.ncbi.nlm.nih.gov regularly. This way, you’ll also protect the relay from getting dirty.

Final Thoughts

A relay is one of the crucial components of an AC unit, but most homeowners usually overlook it during maintenance leading to various electrical issues. Relay issues may also you’re your air conditioner to stop working properly. Nevertheless, the relay may develop issues no matter how well you maintain it.

When the relay develops issues, try to fix it by yourself. So, it’s important to learn how to fix a stuck relay on AC unit and avoid wasting money. In instances where the relay is not fixable, consider replacing it.

References

1.
Common Air Conditioner Problems | Department of Energy
When your air conditioner is not operating properly, there are a few things you can check before calling a service professional.
2.
Pliers Information
Pliers (plyers) are handheld, manually-powered hand tools, often employing serrated jaws, designed for holding, cutting, bending, or manipulation of tough or difficult materials such as wire, sheet metal, or fine machine components.
3.
Characteristics of Air Filters
Air filter is the main equipment in the field of air cleaning technology, and it is an indispensible equipment to create the clean air environment. So it is necessary to know the characteristic of air filters and its design principle so as to use it correctly and effectively.
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