What Homeowners Should Know About Coastal Corrosion

If you’ve lived in Mount Pleasant long enough, you’ve probably seen what salt air can do. And unfortunately, your air conditioner isn’t immune. The same salty breeze that makes life near the marsh so refreshing also carries microscopic salt particles that cling to metal surfaces, including your AC’s coils and fins. Over time, that buildup can corrode key components, reduce efficiency, and shorten your system’s lifespan.

At Dunes Heating and Air Conditioning, we service hundreds of homes across Mount Pleasant, Sullivan’s Island, and Isle of Palms, and corrosion is one of the most common (and preventable) issues we see in coastal systems.

In this blog, our Mount Pleasant AC repair specialists will explore what every Lowcountry homeowner should know.

Why Salt Air Is So Hard on AC Units

Salt is naturally corrosive. When carried through the air, it settles on your outdoor condenser unit—the large metal box that pulls heat from your home.

Mount Pleasant’s climate makes the problem worse:

  • High humidity helps salt stick to surfaces and dissolve into moisture.
  • Constant breezes carry salt inland from the harbor and beaches.
  • Warm temperatures accelerate oxidation and metal breakdown.

Together, that’s a perfect recipe for corrosion—especially on aluminum fins and copper coils, which are both essential to heat exchange. Even if you’re a few miles inland from Shem Creek or Highway 17, your system is still exposed to salt particles year-round.

What Corrosion Actually Does

Corrosion doesn’t destroy a heating and cooling system overnight—it sneaks up slowly. You might notice the following:

  • The outer cabinet showing rust or discoloration.
  • Reduced cooling performance or uneven temperatures.
  • The unit running longer and harder to keep up.
  • Higher energy bills without a clear reason.

Left unchecked, salt corrosion can eat through coils and tubing, leading to refrigerant leaks or compressor failure—two of the most expensive HVAC repairs a homeowner can face.

How to Protect Your AC from Coastal Corrosion

The good news is that with a few simple steps, you can dramatically slow the damage and extend the life of your HVAC system.

1. Rinse the Outdoor Unit Regularly

Every few weeks—especially during the summer—use a garden hose to gently rinse your condenser. It removes salt, sand, and pollen before they can build up. Avoid pressure washers, which can bend the fins or push debris deeper inside.

2. Schedule Routine Coil Cleaning

A professional cleaning once or twice a year clears away mineral deposits and grime that regular rinsing can’t reach. Dunes HVAC technicians use coil-safe solutions designed to remove salt without damaging the metal.

3. Apply Protective Coatings

Anti-corrosion coatings, such as epoxy or polymer sprays, create a barrier between the salt air and your system’s coils. Some new HVAC units even come pre-treated for coastal environments—a smart investment for Mount Pleasant homeowners.

4. Check Placement and Airflow

Ensure your outdoor unit sits on a slightly elevated concrete or composite pad with at least two feet of clearance around it. Good airflow helps dry off moisture after rain and keeps salt from settling.

5. Schedule Preventive Maintenance Twice a Year

A trained technician can spot early signs of corrosion before they become expensive problems. During maintenance, we inspect connections, check refrigerant levels, and look for rust or pitting on the coils and fan blades.

When Replacement Might Make Sense

If your system is more than 10 years old and showing visible rust or efficiency issues, it may be time to upgrade. Modern HVAC units built for coastal regions often feature:

  • Corrosion-resistant aluminum or coated coils
  • Sealed electronics to prevent salt intrusion
  • Improved drainage design for faster drying

These systems cost a bit more upfront but can last years longer in Charleston’s salty, humid air, saving you money over time.

Trust Dunes Heating and Air Conditioning for Reliable Air Conditioning Repair in Mount Pleasant, South Carolina

At Dunes Heating and Air Conditioning, we understand the challenges of coastal living because we live and work here, too. From routine cleanings to AC repair and corrosion-resistant replacements, our team helps Mount Pleasant homeowners protect their comfort season after season. Reach out to schedule your next maintenance with Dunes Heating and Air Conditioning today.