Haier AW07LC2VHA Technical Overview page 44

Cassette Unit Technical Overview
Component Overview
The indoor cassette type units act as evaporator coils
during cooling mode and condenser coils during heating
mode. These units have a built in condensate pump with an
associated condensate level switch. The condensate pump
is capable of lifting water out of the indoor unit. If high water
lift is needed, the water from the cassette pump should be
pumped into a field supplied condensate pump with high lift
power.
Cassette type indoor units can be operated with a
wired controller or a remote control.
Power to operate the indoor unit comes from the
electrical line voltage terminal block at the outdoor
unit. The wiring includes 4 wires, 1, 2, 3 and ground.
Wires 1 and 3 complete the data path. These wires
should always be 14 gauge AWG Stranded type wire.
Splices in wires 1 or 3 may cause communication
errors.
The indoor unit features a multi speed blower motor that
will change speed to match the capacity demand from the
outdoor unit. Separate motors located in the indoor unit
control the operation of the motorized louvers. All of the
louver motors are controlled via commands received from the
remote control. The blower motor is controlled by both the
PAGE 44
Cassette Unit Components
remote control and by commands from the outdoor unit ECU.
Refer to the Remote Control Information in the Reference
section for louver control/remote procedures.
Motor Blower
Unlike typical air handlers found in the US market, these
units have metering devices located in the outdoor unit. The
metering devices are EEV type that are controlled by the
outdoor unit ECU.
Temperature sensors located within the cassette unit include
a pipe temperature sensor and a return air temperature
sensor. The pipe temperature sensor is used to sense the
temperature of the indoor coil in both cooling and heating
modes. The return air sensor sense the temperature of the air
being drawn into the wall mounted unit from the conditioned
space. The operating functions of these sensors is explained
in the Temperature Sensor Function section of this manual.
The indoor unit has a display that communicates system
mode. The indoor unit does not display temperatures
or diagnostic codes. When a wired controller is used,
this information is displayed on the wired controller. It is
recommended to use a wired controller with the cassette unit.
When servicing a diagnostic error, ALWAYS refer to the
outdoor unit code to make diagnostic decisions.
TECHNICAL OVERVIEW
Terminal Block
Pipe Sensor
Ambient Sensor