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ICE CFA1120A-3360A & CGA3180A I&O Manual 03/2021 Rev.5
pressure are increased. The hot refrigerant gas condenses to liquid as heat is transferred to outdoor air
drawn across the condenser by the condenser fan. Liquid refrigerant is metered with a thermal expansion
valve (TXV) into the evaporator to repeat the cycle.
Economizer
The factory installed economizer saves energy and reduces the run time on the compressor and
condenser fan motor by using outside air – when suitable – to cool the shelter.
Note:
The economizer option is currently available on the 1120,1150, 3180, 3240, 3300 and 3360.
On a signal from the wall mounted indoor thermostat that cooling is required, either mechanical
cooling with the compressor or free cooling with the economizer is provided. A factory installed
enthalpy controller determines whether the outside air is sufficiently cool and dry to be used for
cooling. If suitable, the compressor is locked out and the economizer damper opens to bring in
outside air through fresh air hoods located on each side of the air conditioner. The outside air is
filtered with filters in each of the outside air hoods. Integral pressure relief allows the interior air to
exit the shelter, permitting outside air to enter the shelter. The temperature at which the economizer
opens is adjustable from 63°F (17°C) at 50% Relative Humidity to 73°F (23°C) at 50% Relative
Humidity.
After the enthalpy control has activated and outside air is being brought into the building, the mixed
air sensor measures the temperature of the air entering the indoor blower and then modulates the
economizer damper to mix the right proportion of cool outside air with warm indoor air to maintain
50°-63°F (10° - 17°C) air being delivered to the building. This prevents shocking the electronic
components with cold outside air.
The compressor is not permitted to operate when the economizer is functioning.
If the outside air becomes too hot or humid, the economizer damper closes completely, or to a field
selectable minimum open position, and mechanical cooling is activated.
Fresh air hoods with prefilters are field installed on each side of the air conditioner.
CFA (Single Compressor) Units:
The cooling input terminal is terminal (1) of the low voltage terminal
strip. When terminal (1) has 24vac applied the system operates in the cooling mode.
CFA/CGA (Dual Compressor) Units:
The CFA and CGA is factory wired for maximum cooling
utilizing both compressors. If 2 stage compressor operation is desired, the factory installed jumper
between terminals 1 and 2 of the low voltage terminal strip must be removed. The 1st stage cooling input
is terminal 1 of the low voltage terminal strip and the 2nd stage cooling input is terminal 2 of the low
voltage terminal strip. The thermostat must be programmed for 2 stage cooling operation when 2 stage
compressor operation is desired.
Heating Mode
A wall-mounted thermostat controls the heating cycle of models which incorporate resistance heating
elements. On a call for heat, the thermostat closes the heat relay to energize the indoor fan and the
resistance elements.
