Understanding the Codes
That little display is your first line of defense. The dock talk might be confusing, but these codes are straightforward if you know what they mean. Here's the breakdown for the most common faults you'll encounter.
High Pressure Fault (HI PS)
This is the most common and critical error. It means the system is overheating. The number one cause is restricted raw water flow. Before you do anything else, check your sea strainer. It's amazing what a bit of seagrass can do. If that's clear, make sure your seacock is fully open and the pump is primed and running.
Low Pressure Fault (LO PS)
This fault indicates a loss of refrigerant. It's a sealed system, so if you're low, you have a leak. Don't let any bilge rat tell you to just "top it off." That's a temporary fix at best and illegal at worst. A professional needs to find and fix the leak, then recharge the system properly. Running it low will cook your compressor.
Other Common Indicators
Beyond the main pressure faults, other issues can arise. From power problems to sensor failures, here's how to troubleshoot them.
Blank Display Panel
No lights, no action. This is a power issue. Start with the simple stuff: check the AC breaker dedicated to that unit. If it's not tripped, the problem could be the control board fuse or a loose connection. If you've been in heavy seas, it's not uncommon for things to rattle loose.
Unit Icing Up
If you see ice on your evaporator coil, you have an airflow problem or you're low on refrigerant. First, pull out your air filter and clean or replace it. A clogged filter chokes the system. If the filter is clean, it's likely a slow leak, which points back to needing a professional service call.
Still Stumped? We're a Call Away.
Some problems require a seasoned expert. If you've run through the basics and are still scratching your head, don't risk damaging your equipment. The team at Accumar has seen it all and can get your system back to shipshape condition.
We service all Cruisair, Dometic, and other major marine AC brands.
Captain's Maintenance Bulletin
Seasonal checklists, diagnostic tips, and marine AC insights from 25+ years in the field. No fluff — just what works.