"My Boat's AC Stopped Cooling" — Start Here
Marine AC failures usually look the same from the helm: the unit runs, the blower blows, but the air coming out is not cold. The cause is almost never the compressor itself. On a marine system, the cooling comes from raw water moving through a coaxial condenser — and when that water flow stops or drops, the refrigerant pressure climbs, the system trips a high-pressure fault, and the cabin gets hot.
Before you spend money on a repair, a Fixar technician will work the failure tree in order: power and breakers, seacock and strainer, raw-water pump, hoses and condenser, then the refrigerant side. Diagnosis at the dock; no system pulled apart unnecessarily.
The Six Most Common Marine AC Failures
If your boat AC is not cooling, the cause is almost always on this list:
Raw-Water Pump Failure
The centrifugal pump that pulls seawater through the condenser. Common failure modes: seized impeller, corroded electrical connections, lost prime, or a tripped breaker. No water flow, no cooling.
Fouled Seacock or Strainer
Barnacles, eelgrass, and silt clog the strainer basket and the thru-hull. The pump tries to suck water through a wall of debris — flow drops, the condenser starves, and the system overheats.
Air Lock in the Raw-Water Loop
Most marine raw-water pumps are not self-priming. Open a high-point fitting, lose prime at the wrong moment, and the pump spins dry while no water reaches the condenser.
High-Pressure Fault
When raw-water flow drops, refrigerant pressure climbs and the safety switch trips the system. The fault is a symptom — we trace it back to the real cause on the water side before touching refrigerant.
Scaled or Clogged Condenser
Years of seawater leave mineral and biological scale inside the coaxial condenser. Heat transfer drops, run times climb, and eventually the system can no longer keep up — even with the pump running fine.
Low Refrigerant Charge
A slow leak at a flare, schrader valve, or corroded copper line. Only after the water side checks out do we test the sealed circuit — and any refrigerant work is done under EPA Section 608.
How We Diagnose Marine AC at the Dock
Symptom Intake
Quick conversation: what is the boat doing, what fault codes show on the panel, when did it start, and what changed (new slip, recent haul-out, fresh splash).
Power & Controls
Verify shore power, AC breakers, pump breaker, and control board status. A surprising number of "broken" boat AC calls end here.
Raw-Water Path
Seacock open, strainer clean, pump primed and discharging. Look for steady overboard flow — the single best one-second diagnostic on a marine AC system.
Pressures & Temperatures
If the water side is right and the unit still will not cool, we check refrigerant pressures, supply/return air temperatures, and superheat to isolate refrigerant or compressor issues.
Repair Plan & Quote
You get a clear written summary: what is wrong, what we recommend, and what it costs — before any major work begins.
Repair & Verify
Once approved, we complete the repair and verify performance: airflow, supply-air temperature drop, and stable raw-water discharge before we leave the slip.
Dockside & Same-Day Service
Most marine AC failures happen during the season — usually the first hot weekend on the boat. We schedule dockside service from our Brooklyn waterfront base across the NYC harbor and Long Island waterfront. Same-day and weekend service is available subject to technician availability and travel distance to your slip.
Call (929) 351-5179 to describe the symptoms and check availability for your marina.
Marine AC Brands We Service
We service marine air conditioning systems from manufacturers including Dometic, Cruisair, Marine Air Systems, Mermaid, and Webasto. We are an independent service contractor, not a brand dealer — so our diagnosis and recommendations come from what the system actually needs, not what we are trying to sell.
Frequently Asked Questions
Why is my boat AC not cooling?
Nine times out of ten the answer is on the raw-water side: a tripped pump breaker, a fouled strainer or seacock, a failed raw-water pump, an air lock, or a scaled condenser. When seawater flow drops, the refrigerant pressure climbs and the system trips. We work the water side first before touching refrigerant.
What is a raw-water pump and why does it fail?
It is the centrifugal pump that pulls seawater through your AC condenser to carry heat overboard. Common failures: seized or corroded impeller, lost prime, corroded electrical connections, or a tripped breaker. Pumps are wearable parts on a saltwater boat — expect to replace them periodically.
Do you offer same-day dockside marine AC repair?
Same-day and weekend dockside service is available subject to technician availability and travel distance to your slip. Call (929) 351-5179 to describe the symptoms and check availability for your marina.
How do I know if my seacock or strainer is fouled?
Run the AC and look at the overboard raw-water discharge. A steady, full stream means flow is good. A weak trickle, sputter, or no flow at all points to a fouled strainer, closed seacock, blocked thru-hull, or failed pump. The strainer should be inspected at the start of every season and after stirring up bottom growth.
What marine AC brands do you repair?
We service systems from manufacturers including Dometic, Cruisair, Marine Air Systems, Mermaid, and Webasto. We are an independent service contractor, not a brand dealer.
What does marine AC repair cost?
Pricing depends on the failure and the system. A simple strainer clean is a quick visit; a raw-water pump replacement is parts plus labor; a scaled condenser flush or refrigerant repair is a larger job. We provide a written quote after diagnosis — before any major work begins.
Boat AC Not Cooling? Let's Get It Running.
Dockside diagnosis and repair across the Brooklyn waterfront and NYC harbor.
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