Temperature Sensors; Call To Terminate Cooling; Freeze Protection Function; Heat Mode - Haier HSU09VHG(DB)-W Service Manual

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.

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 cool mode.
The outdoor ambient temperature sensor provides the
temperature of the air drawn into the condenser coil of the
outdoor unit.
The defrost temperature sensor provides the temperature
sensed at the output 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 Cooling

The system will call to terminate cooling when the indoor am-
bient temperature sensor is equal to or lower than 2°F of the
room set temperature. The indoor control board will com-
municate to the outdoor control board to de-energize the
compressor. The outdoor fan will run for 60 seconds before
stopping.
The indoor fan motor and louver will continue operating after
cooling has been terminated.
To stop cool mode, press the power button to turn the sys-
tem off, or change to another mode.

Freeze protection function

To prevent freezing of the indoor unit coil during cool mode,
when the compressor operates continuously for 10 seconds
and the temperature of the indoor coil has been below 32°F
for 10 seconds, the compressor will stop, and the error will
be recorded in the malfunction list. The indoor unit fan will
continue to operate. When the temperature of the indoor coil
rises to 45°F for more than 3 minutes the compressor will
restart and the system will continue functioning.

Heat Mode

Overview

The temperature control range in heating mode is 60°F - 86°F.
The temperature set by the remote control and the indoor
unit ambient temperature sensor will determine if a call for
heat is needed. If a call for heat is justified, a temperature
compensation adjustment is automatically added to the
operating parameter and the call is communicated from the
indoor unit to the outdoor unit.
The indoor unit louver will open using a stepper motor. The
indoor fan will not operate at this time.
The outdoor unit will shift the 4-way valve to the heat mode
position and determine the position of the EEV (if equipped)
and speed (frequency) of the compressor. There can be a
delay of up to 3 minutes before the outdoor unit fan and com-
pressor start.
(Tr = room temperature Ts = set temperature)
If Tr ≤ Ts, the outdoor unit will operate and the indoor fan
operates in cold air prevention function
If Tr > Ts+, the outdoor unit turns off and the indoor fan oper-
ates at heat residue sending mode.
If Tr < Ts+, the outdoor unit will restart and the indoor fan
operates in cold air proof mode.
The speed of the indoor fan can be controlled manually by
the user or automatically by the system. The speed can be
changed between HIGH, MEDIUM, and LOW. The predeter-
mined conditions for automatic control are as follows:
High Speed: Tr < Ts
Medium Speed: Ts ≤ Tr ≤ Ts + 4°F
Low Speed: Tr > Ts + 4°F
When the indoor fan is running in automatic mode and there
*Indoor fan control
is no delay when the speed switches from high to low, the
manual control: You can choose high, medium, low and automatic speed control.
indoor fan will maintain high speed for a period of 3 minutes
Automatic: When Tr<Ts, high speed.
before switching to low speed.
When the airflow speed has no delay from the high to low switching, the speed should be d

Cold air proof operation

3 minutes (remain at high speed for 3 minutes.) before the next switch.
At initial start of heat mode, indoor blower will not be turned
*Airgate location control: the location for the airgate can be set according to your needs.
Coldair proof operation
on immediately until indoor coil temperature senses a mini-
1. The indoor operation within 4 minutes after the start up is as the following diagram, the
mum temperature. This period usually takes 30 seconds to 3
can be raised only after the speed has reached a certain level.
minutes depending on the outdoor ambient temperature.
Heat start temp 1
Heat start temp
Heat start temp
Heat start temp
2. 4 minutes after the start up of the indoor fan, the light airflow and the low airflow will be turn
set speed airflow.
4 minutes after the indoor fan starts, the light or low speed
3. In the cold air proof operation, the fan won't stop after the start up.
will switch to the set speed.
4. During the cold air proof operation, the indoor system will continuously send 'indoor hi
signals to the outdoor system.
In cold air proof operation, the fan remains on after startup.
* Residue heat sending. The indoor fan will send the residue heat at a low speed for 12 seco
If other conditions are satisified, when the compressor stops, the indoor system will operate
speed. The indoor fan will stop when the coil temperature is below the 'heat start temp 4'.
Residual heat sending: the indoor fan will operate on low
* Defrosting. When the system receives the defrosting signal from outdoors, the indoor fan
speed for 12 seconds.
and the indoor temperature display won't change. At the time, any indoor coil malfunctio
neglected. When the outdoor defrosting finishes, the coil malfunction will still be neglected
The outdoor unit temperature sensors: outdoor ambient,
compressor has been started up for 30 seconds. The indoor temperature display will not ch
defrost, suction line, and compressor discharge, used in
the system operates at the cold air proof mode.
conjunction with the indoor temperature sensors, indoor
* Automatic heating temperature compensation: when the system enters the heating m
temperature compensation (4) will be added. When the status is switched off, the compen
be erased.

SEQUENCE OF OPERATION

HSU129HG(DB)-SM
When Ts≤Tr≤Ts+2 , medium speed.
When Tr> Ts+2 , low speed.
Set speed
Low speed
2
Light speed
3
Fan/off
4
Fan/off
Wiring Diagrams
Keep the high
speed. The fan
doesn't stop
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