| FAULT | POSSIBLE REASON | CORRECTION |
| Nothing works at all | Air conditioner circuit breaker is off. | Turn circuit breaker on at ship’s panel. |
| Wiring at terminal strip is incorrectly wired | Check wiring diagram; correct if necessary |
| Fan runs but no water flow | Water intake valve is closed | Open valve |
| Strainer or intake is plugged | Clean strainer/intake |
| Hose collapsed, kinked or pinched | Repair/reroute hose |
| Pump relay panel may not be operating properly | Check pump relay panel wiring diagram. With unit breakers and A/C pump breaker on, check input voltage to relay panel. If voltage is not present, a wiring problem exists back to the ship’s panel. With unit on, check voltage at signal terminals (1A & IB, 2A & 2B, etc.) If voltage is not present, a wiring problem exists back to the unit. With voltage present at both locations above, check output terminals to seawater pump. If voltage is not present, either: 1. Signal circuit is defective. Move to a spare circuit if available. 2. Triac is defective on seawater pump circuit. |
| | Replace circuit board if above does not correct problem |
| Fan and Pump run, but no cooling or heating | Selector switch may not be in “Run” position, but rather in “Start” mode | Verify switch setting |
| Compressor not running or trying to start | Thermostat may not be set properly, thus not signaling compressor to start. | Turn counter-clockwise for warmer and clockwise for cooler |
| Wiring terminal to thermostat or selector switch may be disconnected. | Check wiring schematic before reconnecting loose terminals. |
| Fan and Pump run, but no cooling or heating | Seawater intake valve may be closed. | Open valve |
| Compressor operates for only short periods of time. | Seawater strainer or intakes could be plugged. | Check hoses from intake to pump, pump to condensing unit, and condensing unit to overboard to make certain that they have not collapsed, pinched, or kinked. |
| Water pump may be defective. | Check voltage to pump, check pump head and impeller. |
| Fan blows, Pump & Compressor runs, but unit does not heat or cool enough. | Dirty return air filter | Clean filter |
| Check for proper thermostat setting | Turn counter-clockwise for warmer and clockwise for cooler |
| On heat setting, system takes fifteen minutes to stabilize. As the seawater becomes colder, the output of the system is reduced. Note that 45°F (7.2°C) seawater is the coldest recommended operating level. | Give system time to stabilize. Verify seawater temperature. |
| On cooling, the thermostat may be set too cold or supply air may be short cycling causing the evaporator coil to freeze | Check thermostat setting and/or redirect supply air so that it is not directed into the return air stream. |
| | Switch unit into heat until the ice melts. A unit low on refrigerant charge will cause evaporator icing. |
| Low voltage can cause the air conditioning system to cycle off before proper temperature is reached | Check electrical supply source |
| Reduced water flow | Visually check water flow overboard and if low take corrective action |