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Compressor restart is accomplished by manual reset at the
thermostat by turning the selector switch to OFF position and
then to ON position.
Allow unit to operate a minimum of 10 minutes before
checking refrigerant charge.
Heating —
To start unit, turn on main power supply.
Set system selector switch at HEAT position, and set ther-
mostat at a setting above room temperature. Set fan at AUTO
position.
First stage of thermostat energizes the indoor fan, compres-
sor, and outdoor fan; second stage energizes electric heater ele-
ments, if installed. Check heating effects at air supply grille(s).
If electric heaters do not energize, reset limit switch (located
on indoor-fan scroll) by depressing button located between ter-
minals on the switch.
TO SHUT OFF UNIT — Set system selector switch at OFF
position. Resetting thermostat at a position below room tem-
perature temporarily shuts unit off until space temperature falls
below thermostat setting.
Safety Relief —
A soft solder joint at the suction line fit-
ting provides pressure relief under abnormal temperature and
pressure conditions.
Ventilation (Continuous Fan) —
selector switches at ON and OFF positions, respectively. Indoor
fan operates continuously to provide constant air circulation.
Operating Sequence
COOLING, UNITS WITHOUT ECONOMIZER — When
the thermostat calls for cooling, terminals G and Y1 are ener-
gized. The reversing valve solenoid (RVS), indoor-fan contac-
tor (IFC), and compressor contactor no. 1 (C1) are energized
and the indoor-fan motor (IFM), compressor, and outdoor fan
start. The outdoor-fan motor (OFM) runs continuously while
unit is cooling.
COOLING, UNITS WITH DURABLADE ECONO-
MIZER — When the outdoor-air temperature is above the
OAT (outdoor-air temperature) setting and the room thermostat
calls for cooling, the reversing valve solenoid (RVS) and the
compressor contactor are energized to start the compressor and
outdoor-fan motor (OFM). The indoor-fan motor (IFM) is
energized and the economizer damper moves to the minimum
position. After the thermostat is satisfied, the damper moves to
the fully closed position when IFM is deenergized.
When the outdoor-air temperature is below the OAT setting
and the thermostat calls for Y1 and G (cooling), the economiz-
er damper moves to the minimum position when the indoor fan
starts. The first stage of cooling is provided by the economizer.
If the supply-air temperature is above 57 F, a switch on the
supply-air thermostat is closed between the T2 terminal and the
24 vac terminal. This causes the damper to continue to modu-
late open until the supply-air temperature falls below 55 F or
the damper reaches the fully open position.
When the supply-air temperature is between 55 F and 52 F,
the supply-air thermostat has open switches between the T2
and 24 vac terminals and between the T1 and 24 vac terminals.
This causes the economizer damper to remain in an intermedi-
ate open position.
If the supply-air temperature falls below 52 F, a switch on
the supply-air thermostat is closed between the T1 terminal and
the 24 vac terminal. This causes the damper to modulate closed
until the supply-air temperature rises above 55 F or the damper
reaches the minimum position.
When the supply-air temperature is between 55 F and 57 F,
the supply-air thermostat has open switches between the T2
and 24 vac terminals. This causes the economizer damper to re-
main in an intermediate open position.
ments of the conditioned space, economizer cooling is integrat-
ed with mechanical cooling, providing second stage cooling.
The compressor and outdoor fan will be energized and the
position of the economizer damper will be determined by the
supply-air temperature.
sor and OFM will be deenergized. The damper position will be
determined by the supply-air temperature.
shuts off. The damper will move to fully closed position.
COOLING, UNITS WITH ECONOMI$ER — When the
outdoor-air temperature (OAT) is above the ECON SP set point
and the room thermostat calls for Stage 1 cooling (R to G + Y1),
the indoor-fan motor (IFM) is energized and the EconoMi$er
damper modulates to minimum position. The compressor con-
tactor is energized to start the compressor and outdoor-fan motor
(OFM). After the thermostat is satisfied, the damper modulates
to the fully closed position when the IFM is deenergized.
room thermostat calls for Stage 1 cooling (R to G + Y1), the
EconoMi$er modulates to the minimum position when the
IFM is energized. The EconoMi$er provides Stage 1 of cooling
by modulating the return and outdoor air dampers to maintain a
55 F supply air set point. If the supply-air temperature (SAT) is
Set fan and system
greater than 57 F, the EconoMi$er modulates open, allowing a
greater amount of outdoor air to enter the unit. If the SAT drops
below 53 F, the outdoor air damper modulates closed to reduce
the amount of outdoor air. When the SAT is between 53 and
57 F, the EconoMi$er maintains its position.
ments of the conditioned space, and the OAT is above the
MECH CLG LOCKOUT set point, the EconoMi$er integrates
free cooling with mechanical cooling. This is accomplished by
the strategies below.
NOTE: Compressor has a 2-minute Minimum On, Minimum
Off, and Interstage delay timer.
point, the compressors remain off.
HEATING, UNITS WITHOUT ECONOMIZER — Set sys-
tem switch at AUTO. or HEAT position. Set thermostat at de-
sired temperature.
contactor and compressor contactor are energized. The revers-
ing valve solenoid (RVS) is deenergized and switches position,
and the indoor fan, outdoor fan, and compressor are energized.
On economizer units, the economizer blade will move into the
minimum position.
contactor (HC1) is energized and starts the electric heaters.
ature set point, heating stages cycle off. The RVS is reenergized.
34
If the outdoor air alone cannot satisfy the cooling require-
When the second stage of cooling is satisfied, the compres-
When the first stage of cooling is satisfied, the indoor fan
When the OAT is below the ECON SP setting and the
If outdoor air alone cannot satisfy the cooling require-
1. If Y1 is energized, and the room thermostat calls for Y2
(2-stage thermostat), the compressor and OFM are ener-
gized. The position of the EconoMi$er damper is main-
tained at its current value.
2. If Y1 is energized for more than 20 minutes, and Y2 is
not energized (whether or not a 2-stage thermostat is
used), the compressor and OFM are energized. The posi-
tion of the EconoMi$er damper is maintained at its cur-
rent value.
3. If Y1 is energized, and the compressor is already ener-
gized (see Step 2) and the room thermostat calls for Y2,
the compressor continues to operate.
4. If the compressor is energized and the thermostat is satis-
fied, the compressor, the OFM, and IFM are deenergized
and the EconoMi$er modulates closed.
When the OAT is below the MECH CLG LOCKOUT set
When the thermostat calls for heat, the IFC, outdoor-fan
If the thermostat calls for a second stage of heat, the heater
When the space temperature approaches the heating temper-
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