HP - A 2
Sequence Of Operation
16 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). Note: During Charge
Assist™ operation, the STATUS LED will be OFF.
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 contactor coil to turn
ON CPR. At the same time, for the 3 and 5 ton models, a Pulse
Width Modulation (PWM) signal is sent from J3/4 (PWM) plug
to the outdoor fan motor to run at high speed. With the 2 and
4 ton models, the outdoor fan receives power when the ODF-1
relay is energized with 24 volts AC from the control board
terminal T1. A demand message from the comfort control is
sent to the indoor unit for matching, first stage airflow from
the blower motor.
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Note: First stage airflow of 80% CFM is Auto Discovered at
power up however; final CFM is configurable through the
Comfort Control Installer Setup ISU # 0182.
3) Y2 LED: When a request for second stage capacity is sent
from the communicating comfort control, the outdoor control
will respond by sending a 20 volt DC signal from the J5 plug
on the control board to the compressor solenoid. The
Y2 LED will now turn ON and both the Y1 and Y2 LEDs will
remain on while high stage operation is requested. The high
stage demand message for second stage capacity is received
by the indoor unit and the blower motor will go to high speed
without delay.
When a high stage demand is satisfied, the communicating
comfort control removes the second stage capacity request
and the outdoor control responds by removing the 20 volt DC
signal from plug J5 de-energizing the compressor solenoid.
Y2 LED will turn OFF and Y1 LED will remain ON. A demand
message from the comfort control is sent to the indoor unit
blower motor to return to first stage airflow.
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 the MS and the CPR. At the same time, for
3 and 5 ton models, the PWM signal is removed from plug J3/4
(PWM) to the outdoor fan motor and the Y1 LED indicator will
turn OFF. With the 2 and 4 ton models, the 24 volt AC signal is
removed from T1 on the control board de-energizing ODF-
1 removing power from the outdoor fan motor. 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 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 buss e.g. three slow flashes indicates three
communicating devices. A fast flashing COM LED indicates loss
of communication.
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Note: Two-Step compressors always start unloaded. A 5-
second DC solenoid delay will be enforced in the event
that a capacity request begins with 2
nd
stage demand from
the Comfort Control.
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16 SEER
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