Haier AW07LC2VHA Technical Overview page 22

The indoor heat exchanger temperature sensor will monitor
the temperature of the indoor coil to ensure it is hot enough to
prevent blowing cold air. Once adequately warm temperature is
sensed at the indoor coil, the ECU will energize the indoor fan to
a higher speed.
The hot gas entering the indoor coil will condense into a
saturated mix and then be subcooled. The refrigerant will
return to the outdoor unit via the mixed phase small line.
4
Temperature Sensor Tc2
This sensor monitors the temperature of the refrigerant liquid
returning from the indoor coil. If abnormally warm liquid is
sensed, the ECU will make inverter or indoor fan motor speed
changes to compensate.
The liquid will enter the Liquid Line Strainer and will pass
through the OPEN EEV
The refrigerant liquid now enters a receiver where excess
refrigerant will store.
After the liquid leaves the Liquid Receiver, it will enter the
restriction of the OUTDOOR UNIT's EEV. The EEV will drop
the pressure of the liquid to low pressure low temperature.
Heat from the outdoor air will boil off the cold refrigerant.
The outdoor coil absorbs heat from the outdoor air. The
refrigerant vapor boiling from the liquid refrigerant in the
outdoor coil exits the outdoor coil.
5
Temperature Sensor Te
The outdoor coil temperature will be sensed by the Defrost
Sensor. The sensor will use this temperature to maintain EEV
position/superheat adjustment and to calculate when a defrost
cycle is necessary.
6
Temperature Sensor Toci
This temperature sensor is now sensing the suction line
temperature of the refrigerant vapor leaving the outdoor coil.
This temperature is used in calculation of the required position
of the OUTDOOR UNIT EEV for proper superheat adjustments.
The vapor refrigerant will then enter the 4 way valve and
be directed to the Compressor suction accumulator. The
accumulator will trap any liquid refrigerant that may enter the
compressor and potentially damage it.
The vapor will exit the accumulator and enter the compressor.
The refrigeration cycle will continually repeat until the demand
for heating ends.
7
Temperature Sensor Ts
The temperature of the suction gas entering the compressor
PAGE 22
OUTDOOR UNIT SEQUENCE OF OPERATION
Heating Mode Sequence of Operation
OPERATIONS
is monitored by the Suction Temperature Sensor. If abnormal
temperature either hot or cool is detected, the frequency of the
compressor may be adjusted or the system may stop operation
to protect the compressor.
During the call for heating, the indoor air temperature will
get closer to setpoint and demand will ease. The compressor
will reduce frequency as the demand decreases. Should an
additional indoor unit call for heating, the demand will increase
and the compressor speed will increase.
When the temperature setpoint of the indoor units is met, the
indoor units will continue to run but the outdoor unit will shut
off. This is normal operation.