Cooling
The following sequences of operation are based on using a
standard single-stage cooling thermostat.
WITH POWER TO UNIT AND THERMOSTAT IN COOLING
MODE.
1. If the fan switch on the thermostat is in the "ON" position,
the 24 volts at "G" will energize the "K1" relay on the fan
control board, close the "K1" relay contacts, and energize
the indoor blower motor. If the fan switch is in the "AUTO"
position, the blower will operate only when there is a call for
cooling by the thermostat.
2. On a call for cooling, the thermostat will send 24 volts to "Y"
on the fan control board. The 24 volt signal will energize
contactor "M1", and power will be supplied to the compres-
sor and outdoor fan motor. If the fan switch on the thermo-
stat is on the "AUTO" position, the thermostat will also send
a 24 volt signal to "G" on the fan control board and the indoor
blower will operate as indicated in step 1.
3. When the demand for cooling has been satisfied, the "M1"
contactor will be de-energized when the 24 volt "Y" signal
is removed. If the fan switch on the thermostat is energized
when the 24 volt "Y" signal is removed. If the fan switch on
the thermostat is in the "ON" position, the indoor blower will
continue to run. If the fan switch is in the "AUTO" position,
the 24 volt "G" signal will be removed, and after a 60 second
delay, the "K1" relay will open and de-energize the indoor
blower motor.
Heating
WITH POWER TO UNIT AND THERMOSTAT IN HEATING
MODE.
1. If the fan switch on the thermostat is in the "ON" position,
the 24 volts at "G" will energize the "K1" relay contacts, and
energize the indoor blower motor. If the fan switch on the
thermostat is in the "AUTO" position, the blower will operate
only when there is a call for heating by the thermostat.
2. On a call for heating, the thermostat will send 24 volts to
"W1" on the fan control board. The 24 volts signal will
energize relay "K2" on the fan control board, and the first
stage of electric heat will be energized.
3. When the heating demand is satisfied, the electric heat will
be de-energized when the 24 volt "W1" and "W2" signals
are removed. If the fan switch on the thermostat is in the
"ON" position, the indoor blower will continue to run. If the
fan switch is in the "AUTO" position, the "K1" relay will open
and de-energize the indoor blower motor after the appro-
priate time delay.
Please refer to Table 14 and 15 for more information.
SEQUENCE OF OPERATION FOR 018 THRU 042 MODELS
ALSO 048 AND 060 MODELS WITH 575 VOLT
SEQUENCE OF OPERATION FOR 048 AND 060 MODELS
WITH 208/230/460 VOLT
Cooling
The following sequences of operation are based on using a
standard single-stage cooling thermostat.
WITH POWER TO UNIT AND THERMOSTAT IN COOLING
MODE.
1. If the fan switch on the thermostat is in the "ON" position,
the 24 volts at "G" will be sent to the ECM indoor motor and
the blower will operate at the programmed airflow. If the fan
switch is in the "AUTO" position, the blower will operate at
the programmed airflow only when there is a call for cooling
by the thermostat.
2. On a call for cooling, the thermostat will send 24 volts to "Y"
on the fan control board. The 24 volt signal will energize
contactor "M1", and power will be supplied to the compres-
sor and outdoor fan motor. If the fan switch on the thermo-
stat is on the "AUTO" position, the thermostat will also send
a 24 volt signal to "G" on the fan control board and the indoor
blower will operate as indicated in step 1.
3. When the demand for cooling has been satisfied, the "M1"
contactor will be de-energized when the 24 volt "Y" signal
is removed. If the fan switch on the thermostat is in the "ON"
position, the indoor blower will continue to run. If the fan
switch is in the "AUTO" position, the 24 volt "G" signal will
be removed, and after a 30 second delay, the indoor blower
motor will shut down.
Heating
WITH POWER TO UNIT AND THERMOSTAT IN HEATING
MODE.
1. If the fan switch on the thermostat is in the "ON" position,
the 24 volts at "G" will be sent to the ECM indoor motor and
the blower will operate at the programmed airflow. If the fan
switch is in the "AUTO" position, the blower will operate at
the programmed airflow only when there is a call for heating
by the thermostat.
2. On a call for heating, the thermostat will send 24 volts to
"W1" on the fan control board. The 24 volts signal will
energize relay "K2" on the fan control board, and the first
stage of electric heat will be energized. The indoor blower
will operate as indicated in step 1.
3. On units with 2 (two) stages of electric heat, the second
bank of heaters will be energized by a 24 volt signal to "W2"
on the fan control board. After a 20 second delay, the third
bank of heaters will be energized if the unit is so equiped.
4. When the heating demand is satisfied, the electric heat will
be de-energized when the 24 volt "W1" and "W2" signals
are removed. If the fan switch on the thermostat is in the
"ON" position, the indoor blower will continue to run. If the
fan switch is in the "AUTO" position, the indoor motor will
shut off after the appropriate time delay.
Please refer to Table 14 and 15 for more information.
530.46-N2Z
Unitary Products Group
11
