Section II. Operating instructions
4-9 Operating controls and Indicators
Heating and AC selector switch (Figure 4-1) On side of heating element above AC unit. Selects OFF, AC or
HEAT by rotating switch.
AC controls (Figure 4-2) On front of AC unit In workshop.
Left switch control fan and AC unit with settings of OFF/FAN/COOL OFF position turns off both fan and
AC. FAN position turns fan on for use with either AC or heating element COOL position turns on AC and fan
Right switch selects amount of cooling to be obtained from AC unit Turn clockwise to increase cooling,
counterclockwise to decrease cooling
AC electrical switch. Switch handle sticks out of lower right corner of AC unit front bottom panel Turns
electric power ON (upper position) or OFF (lower position).
Heating element controls (Figure 4-2). On dayroom port bulkhead aft of refrigerator. Thermostat control on
upper portion of control box sets temperature desired from heating element Bottom portion of control box
displays a thermometer indicating temperature in the dayroom
The following controls and Indicators are part of the seawater system but are critical to operation
of the AC unit. For details see TM 55-1930-209-14&P-2, Seawater Systems.
Seawater valves SW3 and SW27 in void 2 port (Figure 4-3). SW3 controls water flow from forward searchest to
seawater strainer 3 and SW27 controls flow of cooling water from seawater strainer 3 to cooling water pump.
Seawater valve SW28, in void 1 underneath AC unit (Figure 4-3) Controls flow of cooling water from cooling
water pump to AC unit.
Seawater pressure gauges and their associated valves SW35 (seawater strainer 3 pressure in) and SW36
(seawater strainer pressure out) in void 2 port Gauges show seawater pressure going into strainer 3 and seawater
pressure coming out of strainer 3. A pressure differential of 2 pounds per square inch (psi) or more indicates that
the strainer must be switched and the clogged strainer basket cleaned. See TM 55-1930-209-14&P-2, Seawater
Systems, for details. Valves control water pressure to pressure gauges and should normally remain open.
Seawater valve SW47 in void 2 port (Figure 4-3) Controls flow of seawater from cooling pump to chlonnation unit
Seawater valve SW48 in void 2 port. Controls flow of seawater from seawater pumps to air conditioning unit and
Cooling water pump controller on centerline bulkhead In void 2 port (Figure 4-3). Controls electrical power to
cooling water pump.
4-10 Prestart procedures
Keep doors to ROWPU space and weatherdeck closed. Failure to do so overloads HAC system
and can lead to early failure.
Close doors to ROWPU space and weatherdeck and make sure they remain closed when this system is being
Using vent handle extension stored in the dayroom, open HAC outlets in workshop and dayroom Make sure t
are free from obstructions