SEQUENCE OF OPERATION
PAGE 22
ENGLISH
The indoor unit fan will continue to run at minimum speed until
indoor coil temperature reaches a minimum temperature,
when it will turn off.
If the system detects a malfunction, 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 PCB will activate the display of the indoor unit,
illuminating the display and indicating the set temperature
and current status of the unit.
The indoor unit PCB will signal the stepper motor to open the
louver to a stationary position.
The PCB will power up the indoor fan motor after the out
-
door unit has started and heating of the indoor coil has taken
place (see cold air proof operation). The motor has a feedback
circuit which provides information for controlling the speed of
the fan motor.
Indoor Temperature Sensors
The indoor unit has two sensors that provide temperature in-
formation to the indoor unit main board. The sensors: a room
temperature sensor, and pipe 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 specific to the sensor being
checked.
Communication
The indoor and outdoor unit main boards communicate via a
digital signal on the wire connected to terminal 3 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
to perform the requested function.
Outdoor Unit
Upon a request for heat, the outdoor unit PCB applies power
to the 4-way valve, outdoor fan motor, and compressor. De
-
pending 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 as damage to
the meter may result.
If the room temperature is above the set temperature, yet
lower than 2°F above the set temperature, the system will ad
-
just the running frequency of the compressor automatically.
The outdoor unit main board also controls the position of
the EEV (Electronic Expansion Valve) to regulate the flow of
refrigerant to the outdoor unit evaporator coil.
Outdoor Temperature sensors
Five temperature sensors located in the outdoor unit provide
temperature information to the PCB for control of the system
during heat mode.
The ambient temperature sensor provides the temperature of
the air drawn into the condenser coil.
The defrost temperature sensor A provides the temperature
sensed at the output of the condenser coil.
The defrost temperature sensor B provides the temperature
sensed at the middle of the condenser 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
temperature 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-energize 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 system
off, or change to another mode.
