SEQUENCE OF OPERATION
PAGE 24
ENGLISH
When heating has been satised, the outdoor unit compres-
sor will turn o rst and followed by the outdoor fan. The
4-way valve will de-energize 2 minutes after compressor
stops. The indoor unit fan will continue to run at minimum
speed until indoor coil temperature reaches a minimum tem-
perature and it will turn o. If the system detects a malfunc-
tion, it may shut down or show an error code on the indoor
unit display board and/or outdoor unit main board LED.
Defrost
When the system initiates a call for defrost, the indoor fan
motor stops. The indoor unit display will not change. Any
indoor unit malfunctions will be ignored at this time. The sys-
tem will cycle through the defrost operation. Any indoor unit
malfunctions will be ignored until the compressor restarts
and has been operating for 30 seconds. At the conclusion of
the defrost cycle, the indoor fan will enter the cold air proof
operation. Heat mode resumes.
Automatic Heating Temperature Compensation
When the system enters heating mode, a temperature com-
pensation adjustment is added to the operating parameter.
This adjustment is canceled when exiting heat mode.
Indoor Unit
To enter the heat mode, point the infrared remote controller
at the indoor unit and press the power button, then press the
HEAT mode button if not already set to heat mode.
The signals received by the infrared receiver are relayed to
the main board of the indoor unit to turn the system on and
set it to heat mode.
The indoor unit main board will activate the display on the in-
door unit, illuminating the display, indicating the temperature
and current status of the unit.
The indoor unit main board will signal the louver stepper mo-
tor to open the louver to a stationary position.
The indoor unit main board will power up the indoor fan motor
after the outdoor unit has started and heating of the indoor
coil has taken place (see cold air proof operation). The indoor
fan motor has a feedback circuit which provides the indoor
unit main board with information for controlling the speed of
the fan motor.
Temperature Sensors
The indoor unit has two sensors that provide temperature in-
formation to the indoor unit main board. The indoor ambient
temperature sensor, and coil temperature sensor, are used for
controlling the system during heat mode.
The resistance values of the sensors will vary with tempera-
ture. The resistance to temperature values can be found
using a temperature / resistance chart specic to the sensor
being checked.
Communication
The indoor and outdoor unit main boards communicate via
a digital signal on the wire connected to terminal 3C of each
unit. A splice or break in this wire will cause a communication
error.
When a command is received from the remote control, the
indoor unit main board communicates with the outdoor unit
main board via the terminal 3C wire to perform the requested
function.
Outdoor Unit
Upon a request for heat, the outdoor unit main board applies
power to the 4-way valve, outdoor fan motor and compres-
sor. Depending on system cycling, there may be up to a 3
minute wait period before the compressor and outdoor fan
start.)
NOTE: Do not measure compressor voltages, damage to the
volt meter may result.
If the ambient room temperature is above the set tempera-
ture, yet lower than 2°F above the set temperature, the
system will adjust the running frequency of the compressor
automatically according to changes in ambient temperature.
The outdoor unit main board also controls the position of
the EEV (Electronic Expansion Valve) to regulate the ow of
refrigerant to the unit evaporator coil.
Temperature Sensors
Four temperature sensors located in the outdoor unit provide
temperature information to the outdoor unit main board for
control of the system during heat mode.
The outdoor ambient temperature sensor provides the tem-
perature of the air drawn into the condenser coil.
The defrost temperature sensor provides the temperature
sensed at the output of the outdoor coil.
The suction line temperature sensor provides the tempera-
ture sensed at the incoming suction line pipe.
The compressor discharge sensor provides the temperature
sensed at the discharge pipe of the compressor.
Call to Terminate Heating
The system will call to terminate heating when the indoor
ambient temperature sensor is equal to or higher than 2°F
above the room set temperature. The indoor control board
will communicate to the outdoor control board to de-ener-
gize the compressor. The outdoor fan will run for 60 seconds
before stopping. The 4-way valve will de-energize 2 minutes
after the compressor stops.
To stop heat mode, press the power button to turn the sys-
tem o, or change to another mode.
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