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How to Fix A Stuck Relay On An AC Unit? | Causes & Cure

During the summer hot weather temperatures are high and become unbearable sometimes. All we need is the cool and refreshing breeze from your air conditioner to cool down the body. Whether you’re in your home, office, or any commercial building, the AC unit provides you with a comfortable indoor environment. But what happens when your AC stops turning on?

There are multiple reasons it might stop working. Often, the culprit is a stuck relay switch, which is a common issue that can completely hinder your system’s ability to function properly. It can make your space feel muggy and uncomfortable. So, to fix the stuck relay issue follow the simple steps mentioned in the below part.

What is an AC Relay Switch?

A relay is an electrical component that acts like a switch. It’s used to open and close circuits electronically or electromechanically. Essentially, it allows a low-power electrical signal to control a higher-power circuit. This means a small, low-voltage signal can operate a much larger voltage and current. That’s how it enables control over large devices like air conditioners or other heavy machinery without directly handling high-power circuits.

Note: A relay lifespan is around 5 to 10 years depending on usage and environmental conditions.

9 Signs Your AC Relay Switch is Stuck

Unable to determine if it’s stuck or not? See if any of the issues are happening:

  1. AC Unit Won’t Turn Off: If the AC continues to run even after reaching the set temperature or when turned off, the relay might be stuck.
  2. AC Unit Won’t Turn On: If the AC doesn’t start when you switch it on, a stuck relay could be the culprit.
  3. Unusual Clicking Sounds: Hearing continuous clicking noises from the control panel or relay area can indicate a stuck relay.
  4. Inconsistent Cooling: If the cooling is erratic, it might be due to the relay failing to engage or disengage properly.
  5. Burnt Smell: A burnt or electrical smell near the AC unit can signify a stuck or failing relay.
  6. Visible Damage: Inspect the relay for signs of burning, corrosion, or other physical damage.
  7. Multimeter Test: Using a multimeter to test for continuity can help determine if the relay is stuck in an open or closed position.
  8. Compressor Issues: The compressor might run continuously or not at all, indicating a relay problem.
  9. Increased Energy Bills: A stuck relay causing the AC to run constantly can lead to higher energy consumption and bills.

6 Steps For Fixing A Stuck AC Relay Switch

Step 1: Ensure Safety First

Before you begin any work on your AC unit, it’s crucial to turn off the electricity. Head to your breaker box and switch off the power to avoid any risk of electrical shock. Use a non-contact voltage tester to double-check that no voltage remains in the wires.

Step 2: Access the Relay Switch

Open the panel on the outdoor housing of the AC unit using a screwdriver. This will expose the relay switch and allow you to diagnose the problem. Sometimes, the issue is visible, such as accumulated debris or noticeable damage.

Step 3: Clean the Relay Switch

If the relay appears dirty, cleaning may resolve the issue. Remove the relay and clean its connectors and contacts with a rag dampened with alcohol or vinegar. Use masking tape to protect the wires from damage. Thoroughly rinse the relay to remove any residual cleaning solution and dry it completely.

Step 4: Test the Relay

Before replacing the relay, test it to see if cleaning has fixed the problem. Reattach the relay, restore power, and test the AC unit. If the relay still does not function properly, proceed to the next step.

Step 5: Replace the Relay

If cleaning doesn’t help, the relay likely needs to be replaced. Purchase a precise replacement relay specific to your AC unit’s model. Disconnect the old relay, unscrew it from its socket, and install the new one. Ensure all clips and screws are secured.

Step 6: Final Testing

Once the new relay is in place, switch the power back on at the breaker box and test the AC unit. Check for normal operation and listen for any unusual noises that might indicate further issues.

How To Avoid The AC Relay Being Stuck Again?

Once you make it work again the chances are it can happen again. But what can you do then? These tips will allow the relay to stay in its best performance.

  • Run AC on Schedule

In order to prevent your relay from becoming stuck in your air conditioner. You can use your AC for specific intervals, it will reduce the chances of the relay getting stuck. The excessive heat generated during continuous operation can cause the material in the relay to melt and stick. To prevent this, consider not running the AC when it’s not necessary.

  • Use a Thermostat

Further, a programmable thermostat can also help automate the cooling cycles. It minimizes the risk of human error and reduces unnecessary strain.

  • Keep the Unit Clean

You can also keep the outside unit clean and free from debris. Make sure to clean the coils and replace the HVAC filter as part of your regular maintenance routine. The best time is during spring and fall.

8 Tips We Recommend To Our Clients

  1. Check for Overheating: Monitor the AC unit for signs of overheating, as this can cause relays to stick or fail.
  2. Use a Surge Protector: If you’re not sure if you can use a cord extension with AC or not? Install a surge protector to protect the AC unit from electrical surges that can damage the relay.
  3. Inspect Wiring: Regularly check the wiring connected to the relay for signs of wear, corrosion, or loose connections.
  4. Proper Ventilation: Ensure the AC unit has proper ventilation to avoid overheating, which can affect the relay’s performance.
  5. Handle Relays Carefully: When inspecting or replacing relays, handle them carefully to avoid damage.
  6. Use Quality Parts: Always use high-quality, manufacturer-recommended relays for replacements to ensure compatibility and longevity.
  7. Avoid Moisture: Keep the AC unit dry and protected from excessive moisture levels, which can cause corrosion and affect relay function.
  8. Document Issues: Keep a record of any relay issues, including symptoms and fixes, to help with future troubleshooting.

Know When to Call a Professional

If unsure about diagnosing or fixing a relay issue, it’s best to call a professional HVAC technician. After performing any maintenance or repairs, test the AC unit thoroughly to ensure the relay operates correctly.

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