Mars Air Systems L-2254 - Manual (Page 10)

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English L-2254 Operation
Quick Start Operations Checklist
❑ Ensure seawater intake ball valve (sea cock) is open.
❑ Turn on the a/c circuit breaker. If the seawater pump
has its own circuit breaker, turn that on.
❑ Turn the system on.
❑ Set the desired cabin temperature (set point).
❑ Check for a steady solid stream of water from the
overboard discharge.
❑ Verify that there is steady airflow out of the supply air
grille.
❑ If the unit does not appear to be operating properly,
refer to troubleshooting guide lines.
Note: Do not turn the unit off and immediately turn it
back on. Allow at least 30 seconds for refrigerant
pressure equalization.
Mechanical Control Panel
(MCP) Operation
1. Ensure seawater intake ball valve (sea cock) is open.
2. Turn SYSTEM SWITCH control knob to OFF.
3. Turn on AC circuit breaker. If the seawater pump has
its own circuit breaker, turn that on too. Or, if the pump
is connected to a Pump Relay Panel (PRP), then turn
on that circuit breaker also.
4. Turn the SYSTEM SWITCH control knob to START;
this energizes the fan and seawater pump. Turn
THERMOSTAT control knob to the coolest position by
rotating fully clockwise. If system has reverse cycle,
turn knob counter-clockwise for heat.
5. Check for a steady solid stream of seawater from the
overboard discharge.
6. Turn FAN SPEED control knob clockwise to highest
setting for cooling or counter-clockwise for heating.
7. Verify that the fan is running and that there is steady
airflow out of the supply air grille.
8. Turn the SYSTEM SWITCH to RUN; this will start the
compressor. The indicator light on the control will
illuminate.
9. To set the thermostat, allow sufficient time for the unit
to cool/heat the area to the desired temperature. When
the area is sufficiently cooled/heated, turn the thermo-
stat knob slowly toward the center position until it
clicks once (the indicator light will turn off). The
thermostat is now set to maintain a constant tempera-
ture. While heating, if the ambient temperature is less
than 50°F, set the FAN SPEED control knob to low for
five to ten minutes until the unit begins to heat well,
then increase the fan speed for more heat output and
to prevent the system cycling on high pressure.
The thermostat on the MCP control panel serves to cycle
the compressor on and off and provide an automatic
changeover from cooling to heating (reverse cycle only)
with a 3.5° differential. Rotating the thermostat to the left
after it has been set for cooling will cause the unit to
heat. If you rotate the thermostat to the right, the unit will
cool. If the thermostat is left stationary after being set,
the unit will cycle from cooling to neutral, or heating to
neutral depending on the requirement.
Reverse cycle units have a reversing valve that must be
energized periodically to keep the internal parts moving
freely. To accomplish this, switch the A/C into HEAT for a
few seconds once a month.
Note: Do not turn the unit off and immediately turn it
back on. Wait at least 30 seconds.
OPERATION