OPERATION

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.

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.

L-2254 Operation

10

English

Page 10
Image 10
Mars Air Systems L-2254 manual Mechanical Control Panel MCP Operation, Quick Start Operations Checklist