Mermaid Air Conditioner - Manual (Page 29)

breaker through a dedicated air conditioner circuit breaker to the air conditioner electrical
box. This power is distributed to various components inside the electrical box including
a 115/220 vac to 24 vac reduction transformer. The thermostat utilizes the 24 volts to
activate the appropriate relays inside the electrical box which, when energized, apply 115
or 220 vac power to the blower, compressor and water pump. Through a time-delay
device inside the electrical box, the power is provided to the pump and blower
immediately, followed by the power to the compressor approximately ½ to 1 second
later. This device is advantageous for those “limited power supply” situations by
lowering the initial starting surge. The blower may be operated independently of the
compressor and water pump if only circulating air and not refrigerated air is desired. This
is accomplished by simply placing the FAN switch in the FAN ON position. (Mermaid’s
FX-1 Controls utilize 110v or 220v operation and time delays are automatic in the
programming on the circuit board.)
b) When the HEAT-OFF-COOL switch is placed in the COOL position and the SET
temperature is set below cabin ambient temperature, the thermostat will activate both the
fan and main contactor relays in the electrical box. When the main contactor relay is
activated, 115 vac will be applied to the water pump and fan relay powering the blower,
followed by a ½ to 1 second delay providing power to the start and run capacitors as well
as the high pressure switch. If the high pressure switch is closed, power will pass
through the switch to the compressor safety switch to the "compressor" motor windings.
115 vac power is also applied to the compressor motor "run" and "start" windings from
the start and run capacitors. The compressor will now begin to run along with the
previously running fan and pump.
c) Electric Heat Units: When the HEAT-OFF-COOL switch is placed in the HEAT
position and the SET temperature is set above cabin ambient temperature, the thermostat
will activate the heat contactor relay and the fan relay. When the heat contactor relay is
activated, 115 vac will be applied to the heater coils through a heater thermal fuse. The
heater coils will begin to heat up. At this same instant, the fan relay is activated,
applying 115 vac to the fan which will began to run. The main contactor relay is not
activated in the electric heat mode and the compressor and pump will not run. Not
available in 220v.
d) Heat Pump Units: When the HEAT-OFF-COOL switch is placed in the HEAT
position and the SET temperature is set above cabin ambient temperature, the thermostat
will activate the fan relay and the reversing valve relay. The reversing valve relay will in
turn apply 24 vac activation power to the main contactor relay and the reversing valve
solenoid. The fan relay and main contactor relay will activate as described in paragraph
b) above. When the reversing valve solenoid is activated, a metal bar internal to the
reversing valve will be physically moved directing the system freon to flow through a
different port causing it, in effect, to flow in the opposite direction. This will cause the
evaporator to heat up as described in paragraph 2 above. (Mermaid’s FX-1 Controls
utilize a 110v or 220v reversing valve coil that is or will be provided with the use of this
control.)