Marine AC Flush
& Descaling Service

A marine AC flush — also called descaling — is the process of circulating a chemical descaling solution through the seawater side of a boat's air conditioning condenser. The solution dissolves calcium carbonate, mineral scale, and salt deposits that restrict water flow and reduce cooling efficiency. In Southwest Florida's warm, mineral-rich saltwater, this is the single most important AC maintenance task.

A professional marine AC descaling flush costs $200–$400 per unit in Southwest Florida, depending on unit size, access difficulty, and severity of scale buildup. Multi-unit vessels get volume pricing. Accumar Marine's maintenance plan members pay a flat per-visit rate of $140. Compare that to the $1,500–$3,500 cost of a compressor replacement caused by neglected scale — the flush pays for itself many times over.

In Southwest Florida: every 12 months minimum for seasonal boaters. Liveaboards running AC year-round should flush every 6–8 months. Boats docked in canals with hard water or near construction runoff may need more frequent service. The spring pre-season flush is the most critical — it clears scale that accumulated over winter and ensures your system is ready for the heat.

You can attempt a DIY flush with white vinegar, but it's only about 20% as effective as professional-grade descaling solution. Vinegar (5% acetic acid) struggles to dissolve hardened calcium carbonate deposits. Accumar Descaling Solution is formulated specifically for marine heat exchangers and works 5x faster. A professional flush also includes impeller inspection, strainer service, and refrigerant check — issues a DIY flush won't catch.

We use Accumar Descaling Solution — our own proprietary formula developed through 30+ years of marine AC service in Southwest Florida. It's a phosphoric acid-based solution that dissolves calcium carbonate and mineral scale without damaging copper, cupronickel, or titanium heat exchangers when used as directed. Available for purchase in quart ($20), gallon ($66), and 5-gallon sizes for boat owners who want to supplement between professional services.

A single-unit descaling flush takes 45–90 minutes depending on scale severity. The solution circulates through the condenser for 30–60 minutes while we monitor pH levels — when the pH stabilizes, the scale is dissolved. Multi-unit vessels take 2–4 hours. We perform the service at your dock — no need to haul the boat.

Untreated restriction can reduce seawater flow and heat rejection, contribute to high-pressure faults, and increase operating stress. The rate of buildup and resulting damage varies by water conditions, runtime, equipment, maintenance, and the actual fault. Accumar verifies restriction before recommending a flush.

Warning signs can include reduced cooling, longer runtime, high-pressure faults, or weak overboard discharge, but these symptoms can also have electrical, control, pump, refrigerant, sensor, or compressor causes. Most new non-urgent work is currently scheduled about 3–4 weeks out. Urgent requests are reviewed during business hours. Technician availability, travel, safe access, parts, and response timing are confirmed case by case; first-visit completion and after-hours service are not guaranteed.

We flush and service many Dometic, Marine Air, Cruisair, Webasto, Climma, Mermaid, Flagship, Condaria, Frigoboat, and other marine A/C installations. The procedure depends on access points, condenser materials, system layout, and manufacturer guidance; service scope is confirmed from the installed equipment.

The AC and refrigeration maintenance scope may include descaling, coil cleaning, seawater pump and strainer checks, thermostat review, and refrigerant-system observations as applicable to the installed equipment. Frequency, price, access, and follow-up scheduling are confirmed in the written plan; maintenance does not guarantee uninterrupted operation.