Compressor restart is accomplished by manual reset at the
thermostat by turning the selector switch to OFF position
and then ON position.
Heating —
To start unit, turn on main power supply.
Set thermostat at HEAT position and a setting above room
temperature, fan at AUTO position.
First stage of thermostat energizes the first-stage electric
heater elements; second stage energizes second-stage elec-
tric heater elements if installed. Check heating effects at air
supply grille(s).
If accessory electric heaters do not energize, reset limit
switch (located on evaporator-fan scroll) by depressing but-
ton located between terminals on the switch.
TO SHUT OFF UNIT — Set system selector switch at OFF
position. Resetting heating selector lever below room tem-
perature temporarily shuts unit off until space temperature
falls below thermostat setting.
Safety Relief —
A soft solder joint in the suction line at
the loss-of-charge/low-pressure switch fitting provides
pressure relief under abnormal temperature and pressure
conditions.
Ventilation (Continuous Fan) —
Set fan and sys-
tem selector switches at ON and OFF positions, respec-
tively. Evaporator fan operates continuously to provide con-
stant air circulation.
Operating Sequence
COOLING, 50GJ006 UNITS WITHOUT ECONOMIZER
— When thermostat calls for cooling, terminals G and Y1
are energized. The indoor (evaporator) fan contactor (IFC),
compressor contactor (C), and outdoor (condenser) fan are
energized and the evaporator-fan motor, compressor, and con-
denser fan start. The condenser-fan motor runs continuously
while unit is cooling.
COOLING, 50GJ008,012 UNITS WITHOUT ECONO-
MIZER — When the thermostat calls for cooling, terminals
G and Y1 are energized. The indoor (evaporator) fan con-
tactor (IFC) and compressor contactor no. 1 (C1) are ener-
gized and the evaporator-fan motor, compressor no. 1, and
condenser fan start. The condenser-fan motor runs continu-
ously while unit is cooling. If the thermostat calls for a sec-
ond stage of cooling by energizing Y2, compressor contac-
tor no. 2 (C2) is energized and compressor no. 2 starts.
HEATING, 50GJ006 UNITS WITHOUT ECONOMIZER (If
Accessory Heater is Installed) — Upon a call for heating
through terminal W1, IFC and heater contactor no. 1 (HC1)
are energized. On units equipped for 2 stages of heat, when
additional heat is needed HC2 is energized through W2.
HEATING, 50GJ008,012 UNITS WITHOUT ECONO-
MIZER (If Accessory Heater is Installed) — Upon a call for
heating through terminal W1, IFC and heater contactor no.
1 (HC1) are energized. On units equipped for 2 stages of
heat, when additional heat is needed, HC2 is energized through
W2.
COOLING, 50GJ006 UNITS WITH VARISLIDE™ ECONO-
MIZER — When the outdoor-air temperature is above the
outdoor-air thermostat (OAT) setting and the room thermo-
stat calls for cooling, compressor contactor is energized to
start compressor and the outdoor (condenser) fan motor (OFM).
The indoor (evaporator) fan motor (IFM) is energized and
the economizer damper moves to the minimum position. Af-
ter the thermostat is satisfied, there is a 30-second delay be-
fore the evaporator fan turns off. The damper then moves to
the fully closed position. When using continuous fan, the
damper moves to the minimum position.
When the outdoor-air temperature is below the OAT set-
ting and the thermostat calls for cooling, the economizer damper
moves to the minimum position. If the supply-air tempera-
ture is above 57 F, the damper continues to open until it reaches
the fully open position or until the supply-air temperature
drops below 52 F.
When the supply-air temperature falls between 57 F and
52 F, the damper will remain at an intermediate open posi-
tion. If the supply-air temperature falls below 52 F, the damper
will modulate closed until it reaches the minimum position
or until the supply-air temperature is above 52 F. When the
thermostat is satisfied, the damper moves to the fully closed
position when using AUTO. fan or to the minimum position
when using continuous fan.
If the outdoor air alone cannot satisfy the cooling require-
ments of the conditioned space, economizer cooling is in-
tegrated with mechanical cooling, providing 2 stages of cooling.
Compressor and the condenser fan will be energized and the
position of the economizer damper will be determined by
the supply-air temperature. When the second stage of cool-
ing is satisfied, the compressor and OFM will be deener-
gized. The damper position will be determined by the supply-
air temperature. When the first stage of cooling is satisfied,
there is a 30-second delay before the evaporator fan shuts
off. The damper then moves to the fully closed position. When
using a continuous fan, the damper moves to the minimum
position.
COOLING, 50GJ008,012 UNITS WITH VARISLIDE
ECONOMIZER — When the outdoor-air temperature is above
the OAT setting and the room thermostat calls for cooling,
the compressor contactor no. 1 is energized to start com-
pressor no. 1 and outdoor (condenser) fan motor. The indoor
(evaporator) fan motor (IFM) is energized and the econo-
mizer damper moves to the minimum position. Upon a fur-
ther call for cooling, compressor contactor no. 2 will be en-
ergized, starting compressor no. 2. After the thermostat is
satisfied and the IFM is deenergized, the damper moves to
the fully closed position.
When the outdoor air temperature is below the OAT set-
ting and the thermostat calls for Y1 and G, the economizer
damper moves to the minimum position when the indoor
(evaporator) 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 modulate open until the supply-air tempera-
ture 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 intermediate 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 remain in an intermediate open position.
If the outdoor air alone cannot satisfy the cooling require-
ments of the conditioned space, economizer cooling is in-
tegrated with mechanical cooling, providing second stage
cooling. Compressor no. 1 and outdoor (condenser) fan will
be energized, and the position of the economizer damper will
be determined by the supply-air temperature. Compressor no.
2 is locked out.
26