9. Sequence of Operation
Cooling Operation (PHM324-42)
(1)On a call for cooling (Y)
The indoor fan energizes immediately where as the contactor
energizes after a 5 minute time delay (in case of an initial
start up) starting the compressor and the outdoor fan motor.
(2)When the cooling setpoint has been satisfied
When the cooling demand is met, (Y) de-energizes, shutting
off the compressor, indoor fan and the outdoor fan.
(2) When the heating setpoint has been satisfied
When heating demand is satisfied, W3, W2 and Y2
sequentially de-energize switching the compressor and
the indoor fan into low stage heating. When the low stage
heating demand is met, Y1 de-energizes shutting off the
compressor, indoor fan and the outdoor fan.
Continuous Fan
With the continuous Indoor fan option selected on the thermostat,
G is continuously energized. On 024 - 042 units, the selected
airflow setting is provided. On 048 and 054 units, the system runs
low stage (Y1) airflow for continuous fan operation.
Cooling Operation (PHM348-54)
(1)On a call for cooling
These units utilize a 2 stage indoor thermostat. With a first
stage call for cooling (Y1), the indoor fan (low stage)
energizes immediately where as the contactor energizes
after a 5 minute time delay (incase of an initial start up)
starting the compressor (low stage) and the outdoor fan
motor. If the low stage operation cannot satisfy the cooling
demand, the second stage cooling (Y2) energizes switching
the compressor into high stage cooling through energizing an
internal solenoid valve inside the scroll compressor and
switching the indoor fan into high stage.
(2)When the cooling setpoint has been satisfied
When second stage cooling is satisfied, Y2 de-energizes
switching the compressor and the indoor fan into low stage
cooling. When the low stage cooling demand is met, Y1
de-energizes shutting off the compressor, indoor fan and the
outdoor fan.
Heating Operation (PHM324-42)
(1) On a call for heating ......... :
With a call for heating (Y), the indoor fan (low stage)
energizes immediately where as the contactor energizes
after a 5 minute time delay (incase of an initial start up)
starting the compressor and the outdoor fan motor. If (Y)
cannot satisfy the heating demand, the auxiliary or back up
heat (W2) energizes, incase of staged heating, W3 is
energized if the demand is not met. The highest airflow
selected is run while the electric heat is in operation.
(2) When the heating setpoint has been satisfied
When heating demand is met, W3, W2 and Y sequentially
de-energize shutting off the compressor, indoor fan and
the outdoor fan.
Heating Operation (PHM348-54)
(1) On a call for heating ......... :
With a first stage call for heating (Y1), the indoor fan (low
stage) energizes immediately whereas the contactor
energizes after a 5 minute time delay (in case of an initial
start up) starting the compressor (low stage) and the
outdoor fan motor. Ifthe low stage operation cannot satisfy
the heating demand, the second stage heating (Y2)
energizes switching the compressor into high stage
heating through energizing an internal solenoid valve
inside the scroll compressor and switching the indoor fan
into high stage. The auxiliary or back up heat is controlled
by a third stage (W2). If the demand is not met, W3 is
energized in case of staged heating.
42701 1101 oo
Defrost Mode:
(1) On a call for defrost .........
When the defrost sensor closes in the heating mode, there
is a 30, 60, 90 or 120 minute delay before the defrost mode
begins. This delay is selected by the position of the
dipswitches on the defrost board. Defrost interval timing
can be configured by selection switch 1 and 2. See Figure
10.
1. The backup defrost terminate time is fixed at 10
minutes.
2. The compressor recycle delay timer is 5 minutes.
3. The power interrupt response is minimum 17 msec. to
maximum 35 msec.
4. Quite shift compressor recycle delay is 30 seconds.
In normal defrost mode, the following sequence will
occur after the set delay:
1. Condenser fan off.
2. Reversing valve energized to cooling and auxiliary
electric heat (W2) is energized.
3. After defrost sensor opens or a maximum of 10 minutes;
the condenser fan is energized (after 20 seconds) and the
reversing valve is de-energized to the heat mode. Electric
strip heat is also de-energized (after 15 seconds) except
as required by the thermostat.
4. Should the system indoor thermostat be satisfied during
the defrost cycle, the control will de-energize the reversing
valve and auxiliary heat outputs and "hold" the defrost timer
until the next call for heat, at which time the defrost cycle
will be completed.
Service testing: the pins marked "speed up" when momentarily
shorted together (for 5 seconds) and released, will defeat the 5
minutes recycle delay timer and allow the compressor contactor
to be immediately energized, thus forcing a defrost cycle.
Termination of this forced mode will be by the defrost thermostat
or the 10 minute backup timer, provided the defrost thermostat
was closed when the defrost was "forces." If the defrost
thermostat was not closed, at the time of the "forced defrost," the
defrost mode wil! remain for 30 seconds and then terminate.
Adding Accessories
Low/High Pressure Controls
This unit is equipped with extra low and high pressure ports
located inside the unit panel where the external high and low
pressure ports are installed. This allows for installation of high
and low pressure controls or low ambient controls.
13