Call To Terminate Heating; Auto Mode; Dry Mode; Overview - Haier HSU09VHG(DB)-W Service Manual

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 off, or change to another mode.

Auto Mode

With the system turned on, press the AUTO button on the
remote control. The system will change to the auto mode of
operation.
As the room is cooled or heated, the system will automati-
cally switch between cool mode, fan mode, and heat mode.
There is a minimum 15 minute operating time between mode
changes.

Dry Mode

Overview

The temperature control range in Dry mode is 60°F - 86°F.
This mode is used for the purpose of dehumidification.
(Tr = room temperature Ts = set temperature)
When Tr > Ts + 4°F, the compressor will turn on and the indoor
fan will operate at the set speed.
When Ts ≤ Tr ≤ Ts + 4°F, the compressor will operate at the
high dry frequency for 10 minutes, then at the low dry mode
for 6 minutes. The indoor fan will operate at low speed.
When Tr < Ts, the outdoor unit will stop, and the indoor fan will
stop for 3 minutes, then operate at the low speed option.
Automatic fan speed:
When Tr >= Ts + 9°F, High speed
When Ts + 5.4°F ≤ Tr < Ts + 9°F, Medium speed
When Ts + 3.6°F ≤ Tr < Ts + 5.4°F, Low speed
When Tr < Ts + 3.6°F, Light speed
Note: TURBO and QUIET mode must be set using the remote
controller.
If the outdoor fan is stopped, the indoor fan will pause for 3
minutes.
If the outdoor fan is stopped for more than 3 minutes, and the
compressor is still operating, the system will change to light
speed mode.

Indoor unit

To enter the dry mode, point the infrared remote control at
the indoor unit and press the power button, then press the
DRY mode button if not already set to dry 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 dry mode.
The indoor unit main board will activate the display of the
indoor unit, illuminating the display, indicating the room tem-
perature and current status of the unit.
The indoor unit main board will signal the louver stepper mo-
tor to open the louver to either a stationary position, or one
of several oscillating modes.
As the louver opens, the indoor unit main board will power up
the indoor fan motor, operating the fan at the speed last set.
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
information to the indoor unit main board. The sensors: an
indoor ambient temperature sensor, and pipe temperature
sensor, are used for controlling the system during dry 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
main board via the terminal 3 wire to perform the requested
function.

Outdoor unit

Upon a request for dry mode, the outdoor unit main board
applies power to the outdoor fan motor
and compressor. Depending on system cycling, there may
be up to a 3 minute wait period before the compressor and
outdoor fan start.)
WARNING: Do not measure compressor voltages, damage to
the meter may result.
The outdoor unit main board also controls the position of the
EEV (Electronic Expansion Valve)
to regulate the flow of refrigerant to the indoor unit evapora-
tor coil.
SEQUENCE OF OPERATION PAGE 31