HP - A 6
Sequence Of Operation
20 SEER Sequence of Operation
Operation of the communicating outdoor unit is managed and
monitored by a microprocessor control in the outdoor unit. Heat
and Cool demand messages are transmitted over a data line
from the comfort control to the indoor and outdoor sections of
the system. System mode and stage requests are received by
the outdoor communicating control board and responded to by
providing control outputs to contactor(s), switch-over solenoid
coil, fan motor and various relay components. Operating
conditions like active Defrost, Fault conditions and Charge
Assist™ operation are transmitted from the outdoor control over
the data line to the rest of the communicating system. Additional
information that is communicated to the rest of the system
includes outdoor temperature, type of equipment installed (two-
stage/two-step, heat pump or air conditioner) and tonnage which
are used during the Auto Discover function to set indoor airflow
and configure the comfort control for the equipment installed.
The control has 12 Light Emitting Diodes (LEDs) used as status
and troubleshooting indicators.
Air Conditioner and Heat Pump models
There are three LEDs used specifically to indicate the current
state of equipment readiness and active stage of operation.
1) STATUS LED: During power-up, this LED will flash fast (2
times per second) for approximately 70 seconds. After the
power-up sequence is complete, the STATUS LED will flash a
slow steady pace (1 time per second).
2) Y1 LED: When a request for first stage capacity is sent from
the communicating comfort control, the outdoor control will
respond by turning ON the Y1 LED solid. 24 volts AC will be sent
from the J3/1(Y1) plug energizing MS-LO contactor coil to
turn ON CPR-LO. At the same time, a Pulse Width Modulation
(PWM) signal is sent from J3/4 (PWM) plug to the outdoor fan
motor to run at low speed. A demand message from the
comfort control is sent to the indoor unit for matching, first
stage airflow from the blower motor.
Note: During Charge Assist™ operation, the STATUS LED
will be OFF.
Note: First stage airflow is Auto Discovered at power up
however; final CFM is configurable through the Comfort
Control Installer Setup ISU # 0182. Default CFM is as
follows:
2-ton = 50% CFM 1
st
stage airflow
3-ton = 55% CFM 1
st
stage airflow
4-ton = 50% CFM 1
st
stage airflow
5-ton = 65% CFM 1
st
stage airflow
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3) Y2 LED: When a request for second stage capacity is sent
from the communicating comfort control, the outdoor control
will respond by turning OFF the first stage compressor. 24
volts AC output will be removed from the J3/1 (Y1) plug de-
energizing MS-LO contactor coil to turn OFF CPR-LO. Both
the Y1 and Y2 LEDs begin flashing (1 time per second) as the
Inter-Stage Delay of one minute is enforced. The demand
message for second stage capacity is received by the indoor
unit and the blower motor will go to high speed without delay.
When the one minute Inter-Stage Delay is complete, the outdoor
control will send 24 volts AC from the J3/2 (Y2) plug
energizing MS-HI contactor coil to turn ON CPR-HI. At the
same time, a high speed PWM signal is sent to the outdoor fan
motor from plug J3/4 (PWM) and both Y1 and Y2 LED
indicators will be ON solid.
When a high stage demand is satisfied, the communicating
comfort control removes the second stage capacity request
and the outdoor control responds by removing 24 volts AC
from plug J3/2 (Y2) de-energizing MS-HI contactor coil to
turn OFF CPR-HI. Y2 LED will turn OFF and the Y1 LED begins
flashing (1 time per second) as the Inter Stage Delay of one
minute is enforced. Without delay, a demand message from the
comfort control is sent to the indoor unit for matching first
stage airflow from the blower motor. Once the outdoor Inter-
Stage Delay is complete, the outdoor control will send 24
volts AC from the J3/1 (Y1) plug energizing MS-LO contactor
coil to turn ON CPR-LO. At the same time, a low speed
PWM signal is sent to the outdoor fan motor from plug J3/4
(PWM) and the Y1 LED indicator will be ON solid.
When a request for first stage capacity is satisfied, the
communicating comfort control removes the demand message
from the outdoor and indoor controls. The outdoor control
responds by removing 24 volt AC from the J3/1 (Y1) plug
de-energizing MS-LO to turn OFF CPR-LO. At the same
time the low speed PWM signal is removed from plug J3/4 (PWM)
to the outdoor fan motor and the Y1 LED indicator will turn
OFF. The indoor blower will also turn off at this time unless
continuous fan ON is selected or after any programmed blower-
off delay expires.
4) FAULT LED: Utilized specifically to notify the technician of a
situation related to the performance of the outdoor unit. In total,
there are fourteen faults that the outdoor unit is capable of
detecting and reporting locally to the user. In a communicating
environment, there are seven critical alerts (out of the fourteen
faults total) that could be transmitted to the comfort control to
notify the homeowner of a potential problem.
5) COM LED: Used to confirm successful communications and
to identify the number of devices on the data line or
communication bus e.g. three slow flashes indicates three
communicating devices. A fast flashing COM LED indicates loss
of communication.
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20 SEER
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